diff --git a/src/wp-includes/blocks.php b/src/wp-includes/blocks.php
index 2ec3a07e3e..98d8f10d5c 100644
--- a/src/wp-includes/blocks.php
+++ b/src/wp-includes/blocks.php
@@ -112,3 +112,40 @@ function get_dynamic_block_names() {
 
 	return $dynamic_block_names;
 }
+
+/**
+ * Parses blocks out of a content string.
+ *
+ * @since 5.0.0
+ *
+ * @param  string $content Post content.
+ * @return array  Array of parsed block objects.
+ */
+function parse_blocks( $content ) {
+	/*
+	 * If there are no blocks in the content, return a single block, rather
+	 * than wasting time trying to parse the string.
+	 */
+	if ( ! has_blocks( $content ) ) {
+		return array(
+			array(
+				'blockName'   => null,
+				'attrs'       => array(),
+				'innerBlocks' => array(),
+				'innerHTML'   => $content,
+			),
+		);
+	}
+
+	/**
+	 * Filter to allow plugins to replace the server-side block parser
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param string $parser_class Name of block parser class
+	 */
+	$parser_class = apply_filters( 'block_parser_class', 'WP_Block_Parser' );
+
+	$parser = new $parser_class();
+	return $parser->parse( $content );
+}
diff --git a/src/wp-includes/class-wp-block-parser.php b/src/wp-includes/class-wp-block-parser.php
new file mode 100644
index 0000000000..78b6921787
--- /dev/null
+++ b/src/wp-includes/class-wp-block-parser.php
@@ -0,0 +1,473 @@
+<?php
+
+/**
+ * Class WP_Block_Parser_Block
+ *
+ * Holds the block structure in memory
+ *
+ * @since 3.8.0
+ */
+class WP_Block_Parser_Block {
+	/**
+	 * Name of block
+	 *
+	 * @example "core/paragraph"
+	 *
+	 * @since 3.8.0
+	 * @var string
+	 */
+	public $blockName;
+
+	/**
+	 * Optional set of attributes from block comment delimiters
+	 *
+	 * @example null
+	 * @example array( 'columns' => 3 )
+	 *
+	 * @since 3.8.0
+	 * @var array|null
+	 */
+	public $attrs;
+
+	/**
+	 * List of inner blocks (of this same class)
+	 *
+	 * @since 3.8.0
+	 * @var WP_Block_Parser_Block[]
+	 */
+	public $innerBlocks;
+
+	/**
+	 * Resultant HTML from inside block comment delimiters
+	 * after removing inner blocks
+	 *
+	 * @example "...Just <!-- wp:test /--> testing..." -> "Just testing..."
+	 *
+	 * @since 3.8.0
+	 * @var string
+	 */
+	public $innerHTML;
+
+	function __construct( $name, $attrs, $innerBlocks, $innerHTML ) {
+		$this->blockName   = $name;
+		$this->attrs       = $attrs;
+		$this->innerBlocks = $innerBlocks;
+		$this->innerHTML   = $innerHTML;
+	}
+}
+
+/**
+ * Class WP_Block_Parser_Frame
+ *
+ * Holds partial blocks in memory while parsing
+ *
+ * @internal
+ * @since 3.8.0
+ */
+class WP_Block_Parser_Frame {
+	/**
+	 * Full or partial block
+	 *
+	 * @since 3.8.0
+	 * @var WP_Block_Parser_Block
+	 */
+	public $block;
+
+	/**
+	 * Byte offset into document for start of parse token
+	 *
+	 * @since 3.8.0
+	 * @var int
+	 */
+	public $token_start;
+
+	/**
+	 * Byte length of entire parse token string
+	 *
+	 * @since 3.8.0
+	 * @var int
+	 */
+	public $token_length;
+
+	/**
+	 * Byte offset into document for after parse token ends
+	 * (used during reconstruction of stack into parse production)
+	 *
+	 * @since 3.8.0
+	 * @var int
+	 */
+	public $prev_offset;
+
+	/**
+	 * Byte offset into document where leading HTML before token starts
+	 *
+	 * @since 3.8.0
+	 * @var int
+	 */
+	public $leading_html_start;
+
+	function __construct( $block, $token_start, $token_length, $prev_offset = null, $leading_html_start = null ) {
+		$this->block              = $block;
+		$this->token_start        = $token_start;
+		$this->token_length       = $token_length;
+		$this->prev_offset        = isset( $prev_offset ) ? $prev_offset : $token_start + $token_length;
+		$this->leading_html_start = $leading_html_start;
+	}
+}
+
+/**
+ * Class WP_Block_Parser
+ *
+ * Parses a document and constructs a list of parsed block objects
+ *
+ * @since 3.8.0
+ * @since 4.0.0 returns arrays not objects, all attributes are arrays
+ */
+class WP_Block_Parser {
+	/**
+	 * Input document being parsed
+	 *
+	 * @example "Pre-text\n<!-- wp:paragraph -->This is inside a block!<!-- /wp:paragraph -->"
+	 *
+	 * @since 3.8.0
+	 * @var string
+	 */
+	public $document;
+
+	/**
+	 * Tracks parsing progress through document
+	 *
+	 * @since 3.8.0
+	 * @var int
+	 */
+	public $offset;
+
+	/**
+	 * List of parsed blocks
+	 *
+	 * @since 3.8.0
+	 * @var WP_Block_Parser_Block[]
+	 */
+	public $output;
+
+	/**
+	 * Stack of partially-parsed structures in memory during parse
+	 *
+	 * @since 3.8.0
+	 * @var WP_Block_Parser_Frame[]
+	 */
+	public $stack;
+
+	/**
+	 * Parses a document and returns a list of block structures
+	 *
+	 * When encountering an invalid parse will return a best-effort
+	 * parse. In contrast to the specification parser this does not
+	 * return an error on invalid inputs.
+	 *
+	 * @since 3.8.0
+	 *
+	 * @param string $document
+	 * @return WP_Block_Parser_Block[]
+	 */
+	function parse( $document ) {
+		$this->document = $document;
+		$this->offset   = 0;
+		$this->output   = array();
+		$this->stack    = array();
+
+		do {
+			// twiddle our thumbs
+		} while ( $this->proceed() );
+
+		return $this->output;
+	}
+
+	/**
+	 * Processes the next token from the input document
+	 * and returns whether to proceed eating more tokens
+	 *
+	 * This is the "next step" function that essentially
+	 * takes a token as its input and decides what to do
+	 * with that token before descending deeper into a
+	 * nested block tree or continuing along the document
+	 * or breaking out of a level of nesting.
+	 *
+	 * @internal
+	 * @since 3.8.0
+	 * @return bool
+	 */
+	function proceed() {
+		$next_token = $this->next_token();
+		list( $token_type, $block_name, $attrs, $start_offset, $token_length ) = $next_token;
+		$stack_depth = count( $this->stack );
+
+		// we may have some HTML soup before the next block
+		$leading_html_start = $start_offset > $this->offset ? $this->offset : null;
+
+		switch ( $token_type ) {
+			case 'no-more-tokens':
+				// if not in a block then flush output
+				if ( 0 === $stack_depth ) {
+					$this->add_freeform();
+					return false;
+				}
+
+				/*
+				 * Otherwise we have a problem
+				 * This is an error
+				 *
+				 * we have options
+				 * - treat it all as freeform text
+				 * - assume an implicit closer (easiest when not nesting)
+				 */
+
+				// for the easy case we'll assume an implicit closer
+				if ( 1 === $stack_depth ) {
+					$this->add_block_from_stack();
+					return false;
+				}
+
+				/*
+				 * for the nested case where it's more difficult we'll
+				 * have to assume that multiple closers are missing
+				 * and so we'll collapse the whole stack piecewise
+				 */
+				while ( 0 < count( $this->stack ) ) {
+					$this->add_block_from_stack();
+				}
+				return false;
+
+			case 'void-block':
+				/*
+				 * easy case is if we stumbled upon a void block
+				 * in the top-level of the document
+				 */
+				if ( 0 === $stack_depth ) {
+					if ( isset( $leading_html_start ) ) {
+						$this->output[] = (array) self::freeform( substr(
+							$this->document,
+							$leading_html_start,
+							$start_offset - $leading_html_start
+						) );
+					}
+
+					$this->output[] = (array) new WP_Block_Parser_Block( $block_name, $attrs, array(), '' );
+					$this->offset = $start_offset + $token_length;
+					return true;
+				}
+
+				// otherwise we found an inner block
+				$this->add_inner_block(
+					new WP_Block_Parser_Block( $block_name, $attrs, array(), '' ),
+					$start_offset,
+					$token_length
+				);
+				$this->offset = $start_offset + $token_length;
+				return true;
+
+			case 'block-opener':
+				// track all newly-opened blocks on the stack
+				array_push( $this->stack, new WP_Block_Parser_Frame(
+					new WP_Block_Parser_Block( $block_name, $attrs, array(), '' ),
+					$start_offset,
+					$token_length,
+					$start_offset + $token_length,
+					$leading_html_start
+				) );
+				$this->offset = $start_offset + $token_length;
+				return true;
+
+			case 'block-closer':
+				/*
+				 * if we're missing an opener we're in trouble
+				 * This is an error
+				 */
+				if ( 0 === $stack_depth ) {
+					/*
+					 * we have options
+					 * - assume an implicit opener
+					 * - assume _this_ is the opener
+					 * - give up and close out the document
+					 */
+					$this->add_freeform();
+					return false;
+				}
+
+				// if we're not nesting then this is easy - close the block
+				if ( 1 === $stack_depth ) {
+					$this->add_block_from_stack( $start_offset );
+					$this->offset = $start_offset + $token_length;
+					return true;
+				}
+
+				/*
+				 * otherwise we're nested and we have to close out the current
+				 * block and add it as a new innerBlock to the parent
+				 */
+				$stack_top = array_pop( $this->stack );
+				$stack_top->block->innerHTML .= substr( $this->document, $stack_top->prev_offset, $start_offset - $stack_top->prev_offset );
+				$stack_top->prev_offset = $start_offset + $token_length;
+
+				$this->add_inner_block(
+					$stack_top->block,
+					$stack_top->token_start,
+					$stack_top->token_length,
+					$start_offset + $token_length
+				);
+				$this->offset = $start_offset + $token_length;
+				return true;
+
+			default:
+				// This is an error
+				$this->add_freeform();
+				return false;
+		}
+	}
+
+	/**
+	 * Scans the document from where we last left off
+	 * and finds the next valid token to parse if it exists
+	 *
+	 * Returns the type of the find: kind of find, block information, attributes
+	 *
+	 * @internal
+	 * @since 3.8.0
+	 * @return array
+	 */
+	function next_token() {
+		$matches = null;
+
+		/*
+		 * aye the magic
+		 * we're using a single RegExp to tokenize the block comment delimiters
+		 * we're also using a trick here because the only difference between a
+		 * block opener and a block closer is the leading `/` before `wp:` (and
+		 * a closer has no attributes). we can trap them both and process the
+		 * match back in PHP to see which one it was.
+		 */
+		$has_match = preg_match(
+			'/<!--\s+(?<closer>\/)?wp:(?<namespace>[a-z][a-z0-9_-]*\/)?(?<name>[a-z][a-z0-9_-]*)\s+(?<attrs>{(?:(?!}\s+-->).)+?}\s+)?(?<void>\/)?-->/s',
+			$this->document,
+			$matches,
+			PREG_OFFSET_CAPTURE,
+			$this->offset
+		);
+
+		// we have no more tokens
+		if ( 0 === $has_match ) {
+			return array( 'no-more-tokens', null, null, null, null );
+		}
+
+		list( $match, $started_at ) = $matches[ 0 ];
+
+		$length    = strlen( $match );
+		$is_closer = isset( $matches[ 'closer' ] ) && -1 !== $matches[ 'closer' ][ 1 ];
+		$is_void   = isset( $matches[ 'void' ] ) && -1 !== $matches[ 'void' ][ 1 ];
+		$namespace = $matches[ 'namespace' ];
+		$namespace = ( isset( $namespace ) && -1 !== $namespace[ 1 ] ) ? $namespace[ 0 ] : 'core/';
+		$name      = $namespace . $matches[ 'name' ][ 0 ];
+		$has_attrs = isset( $matches[ 'attrs' ] ) && -1 !== $matches[ 'attrs' ][ 1 ];
+
+		/*
+		 * Fun fact! It's not trivial in PHP to create "an empty associative array" since all arrays
+		 * are associative arrays. If we use `array()` we get a JSON `[]`
+		 */
+		$attrs = $has_attrs
+			? json_decode( $matches[ 'attrs' ][ 0 ], /* as-associative */ true )
+			: json_decode( '{}', /* don't ask why, just verify in PHP */ false );
+
+		/*
+		 * This state isn't allowed
+		 * This is an error
+		 */
+		if ( $is_closer && ( $is_void || $has_attrs ) ) {
+			// we can ignore them since they don't hurt anything
+		}
+
+		if ( $is_void ) {
+			return array( 'void-block', $name, $attrs, $started_at, $length );
+		}
+
+		if ( $is_closer ) {
+			return array( 'block-closer', $name, null, $started_at, $length );
+		}
+
+		return array( 'block-opener', $name, $attrs, $started_at, $length );
+	}
+
+	/**
+	 * Returns a new block object for freeform HTML
+	 *
+	 * @internal
+	 * @since 3.9.0
+	 *
+	 * @param string $innerHTML HTML content of block
+	 * @return WP_Block_Parser_Block freeform block object
+	 */
+	static function freeform( $innerHTML ) {
+		return new WP_Block_Parser_Block( null, array(), array(), $innerHTML );
+	}
+
+	/**
+	 * Pushes a length of text from the input document
+	 * to the output list as a freeform block
+	 *
+	 * @internal
+	 * @since 3.8.0
+	 * @param null $length how many bytes of document text to output
+	 */
+	function add_freeform( $length = null ) {
+		$length = $length ? $length : strlen( $this->document ) - $this->offset;
+
+		if ( 0 === $length ) {
+			return;
+		}
+
+		$this->output[] = (array) self::freeform( substr( $this->document, $this->offset, $length ) );
+	}
+
+	/**
+	 * Given a block structure from memory pushes
+	 * a new block to the output list
+	 *
+	 * @internal
+	 * @since 3.8.0
+	 * @param WP_Block_Parser_Block $block the block to add to the output
+	 * @param int $token_start byte offset into the document where the first token for the block starts
+	 * @param int $token_length byte length of entire block from start of opening token to end of closing token
+	 * @param int|null $last_offset last byte offset into document if continuing form earlier output
+	 */
+	function add_inner_block( WP_Block_Parser_Block $block, $token_start, $token_length, $last_offset = null ) {
+		$parent = $this->stack[ count( $this->stack ) - 1 ];
+		$parent->block->innerBlocks[] = $block;
+		$parent->block->innerHTML .= substr( $this->document, $parent->prev_offset, $token_start - $parent->prev_offset );
+		$parent->prev_offset = $last_offset ? $last_offset : $token_start + $token_length;
+	}
+
+	/**
+	 * Pushes the top block from the parsing stack to the output list
+	 *
+	 * @internal
+	 * @since 3.8.0
+	 * @param int|null $end_offset byte offset into document for where we should stop sending text output as HTML
+	 */
+	function add_block_from_stack( $end_offset = null ) {
+		$stack_top   = array_pop( $this->stack );
+		$prev_offset = $stack_top->prev_offset;
+
+		$stack_top->block->innerHTML .= isset( $end_offset )
+			? substr( $this->document, $prev_offset, $end_offset - $prev_offset )
+			: substr( $this->document, $prev_offset );
+
+		if ( isset( $stack_top->leading_html_start ) ) {
+			$this->output[] = (array) self::freeform( substr(
+				$this->document,
+				$stack_top->leading_html_start,
+				$stack_top->token_start - $stack_top->leading_html_start
+			) );
+		}
+
+		$this->output[] = (array) $stack_top->block;
+	}
+}
diff --git a/src/wp-settings.php b/src/wp-settings.php
index 4ae30df9ca..fbd231d45a 100644
--- a/src/wp-settings.php
+++ b/src/wp-settings.php
@@ -246,6 +246,7 @@ require( ABSPATH . WPINC . '/rest-api/search/class-wp-rest-search-handler.php' )
 require( ABSPATH . WPINC . '/rest-api/search/class-wp-rest-post-search-handler.php' );
 require( ABSPATH . WPINC . '/class-wp-block-type.php' );
 require( ABSPATH . WPINC . '/class-wp-block-type-registry.php' );
+require( ABSPATH . WPINC . '/class-wp-block-parser.php' );
 require( ABSPATH . WPINC . '/blocks.php' );
 
 $GLOBALS['wp_embed'] = new WP_Embed();
diff --git a/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.html b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.html
new file mode 100644
index 0000000000..220f8b60c8
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.html
@@ -0,0 +1 @@
+<!-- wp:core/4-invalid /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.json b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.json
new file mode 100644
index 0000000000..3439923f41
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<p><!-- wp:core/4-invalid /--></p>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<p><!-- wp:core/4-invalid /--></p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.parsed.json b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.parsed.json
new file mode 100644
index 0000000000..2dfce101b4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.parsed.json
@@ -0,0 +1,8 @@
+[
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "<!-- wp:core/4-invalid /-->\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.serialized.html b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.serialized.html
new file mode 100644
index 0000000000..fe35001a46
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__4-invalid-starting-letter.serialized.html
@@ -0,0 +1 @@
+<p><!-- wp:core/4-invalid /--></p>
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives.html b/tests/phpunit/data/blocks/fixtures/core__archives.html
new file mode 100644
index 0000000000..dbed6fec17
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives.html
@@ -0,0 +1 @@
+<!-- wp:archives {"displayAsDropdown":false,"showPostCounts":false} /-->
\ No newline at end of file
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives.json b/tests/phpunit/data/blocks/fixtures/core__archives.json
new file mode 100644
index 0000000000..ad43f4051a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/archives",
+        "isValid": true,
+        "attributes": {
+            "displayAsDropdown": false,
+            "showPostCounts": false
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives.parsed.json b/tests/phpunit/data/blocks/fixtures/core__archives.parsed.json
new file mode 100644
index 0000000000..fab690ff93
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives.parsed.json
@@ -0,0 +1,11 @@
+[
+    {
+        "blockName": "core/archives",
+        "attrs": {
+            "displayAsDropdown": false,
+            "showPostCounts": false
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives.serialized.html b/tests/phpunit/data/blocks/fixtures/core__archives.serialized.html
new file mode 100644
index 0000000000..b892875237
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives.serialized.html
@@ -0,0 +1 @@
+<!-- wp:archives /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.html b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.html
new file mode 100644
index 0000000000..cce02a6a1a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.html
@@ -0,0 +1 @@
+<!-- wp:archives {"displayAsDropdown":false,"showPostCounts":true} /-->
\ No newline at end of file
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.json b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.json
new file mode 100644
index 0000000000..0c1514e413
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/archives",
+        "isValid": true,
+        "attributes": {
+            "displayAsDropdown": false,
+            "showPostCounts": true
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.parsed.json b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.parsed.json
new file mode 100644
index 0000000000..cd58cbf969
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.parsed.json
@@ -0,0 +1,11 @@
+[
+    {
+        "blockName": "core/archives",
+        "attrs": {
+            "displayAsDropdown": false,
+            "showPostCounts": true
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.serialized.html b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.serialized.html
new file mode 100644
index 0000000000..e294016710
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__archives__showPostCounts.serialized.html
@@ -0,0 +1 @@
+<!-- wp:archives {"showPostCounts":true} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__audio.html b/tests/phpunit/data/blocks/fixtures/core__audio.html
new file mode 100644
index 0000000000..cfa3f20267
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__audio.html
@@ -0,0 +1,5 @@
+<!-- wp:core/audio {"align":"right"} -->
+<figure class="wp-block-audio alignright">
+    <audio controls="" src="https://media.simplecast.com/episodes/audio/80564/draft-podcast-51-livePublish2.mp3"></audio>
+</figure>
+<!-- /wp:core/audio -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__audio.json b/tests/phpunit/data/blocks/fixtures/core__audio.json
new file mode 100644
index 0000000000..f9acbfdd8c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__audio.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/audio",
+        "isValid": true,
+        "attributes": {
+            "src": "https://media.simplecast.com/episodes/audio/80564/draft-podcast-51-livePublish2.mp3",
+            "caption": "",
+            "autoplay": false,
+            "loop": false,
+            "align": "right"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-audio alignright\">\n    <audio controls=\"\" src=\"https://media.simplecast.com/episodes/audio/80564/draft-podcast-51-livePublish2.mp3\"></audio>\n</figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__audio.parsed.json b/tests/phpunit/data/blocks/fixtures/core__audio.parsed.json
new file mode 100644
index 0000000000..33926c0b88
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__audio.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/audio",
+        "attrs": {
+            "align": "right"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-audio alignright\">\n    <audio controls=\"\" src=\"https://media.simplecast.com/episodes/audio/80564/draft-podcast-51-livePublish2.mp3\"></audio>\n</figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__audio.serialized.html b/tests/phpunit/data/blocks/fixtures/core__audio.serialized.html
new file mode 100644
index 0000000000..f7b69332aa
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__audio.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:audio {"align":"right"} -->
+<figure class="wp-block-audio alignright"><audio controls src="https://media.simplecast.com/episodes/audio/80564/draft-podcast-51-livePublish2.mp3"></audio></figure>
+<!-- /wp:audio -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__block.html b/tests/phpunit/data/blocks/fixtures/core__block.html
new file mode 100644
index 0000000000..25cde6619b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__block.html
@@ -0,0 +1 @@
+<!-- wp:core/block {"ref":123} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__block.json b/tests/phpunit/data/blocks/fixtures/core__block.json
new file mode 100644
index 0000000000..da89e970b4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__block.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/block",
+        "isValid": true,
+        "attributes": {
+            "ref": 123
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__block.parsed.json b/tests/phpunit/data/blocks/fixtures/core__block.parsed.json
new file mode 100644
index 0000000000..61b65e317a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__block.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/block",
+        "attrs": {
+            "ref": 123
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__block.serialized.html b/tests/phpunit/data/blocks/fixtures/core__block.serialized.html
new file mode 100644
index 0000000000..65efadb46d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__block.serialized.html
@@ -0,0 +1 @@
+<!-- wp:block {"ref":123} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__button__center.html b/tests/phpunit/data/blocks/fixtures/core__button__center.html
new file mode 100644
index 0000000000..ce1262f706
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__button__center.html
@@ -0,0 +1,3 @@
+<!-- wp:core/button {"align":"center"} -->
+<div class="wp-block-button aligncenter"><a class="wp-block-button__link" href="https://github.com/WordPress/gutenberg">Help build Gutenberg</a></div>
+<!-- /wp:core/button -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__button__center.json b/tests/phpunit/data/blocks/fixtures/core__button__center.json
new file mode 100644
index 0000000000..7334b3f483
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__button__center.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/button",
+        "isValid": true,
+        "attributes": {
+            "url": "https://github.com/WordPress/gutenberg",
+            "text": "Help build Gutenberg",
+            "align": "center"
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-button aligncenter\"><a class=\"wp-block-button__link\" href=\"https://github.com/WordPress/gutenberg\">Help build Gutenberg</a></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__button__center.parsed.json b/tests/phpunit/data/blocks/fixtures/core__button__center.parsed.json
new file mode 100644
index 0000000000..0094e8f264
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__button__center.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/button",
+        "attrs": {
+            "align": "center"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-button aligncenter\"><a class=\"wp-block-button__link\" href=\"https://github.com/WordPress/gutenberg\">Help build Gutenberg</a></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__button__center.serialized.html b/tests/phpunit/data/blocks/fixtures/core__button__center.serialized.html
new file mode 100644
index 0000000000..3d88c7ec1a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__button__center.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:button {"align":"center"} -->
+<div class="wp-block-button aligncenter"><a class="wp-block-button__link" href="https://github.com/WordPress/gutenberg">Help build Gutenberg</a></div>
+<!-- /wp:button -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__categories.html b/tests/phpunit/data/blocks/fixtures/core__categories.html
new file mode 100644
index 0000000000..89dd1be4ab
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__categories.html
@@ -0,0 +1 @@
+<!-- wp:core/categories {"showPostCounts":false,"displayAsDropdown":false,"showHierarchy":false} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__categories.json b/tests/phpunit/data/blocks/fixtures/core__categories.json
new file mode 100644
index 0000000000..ff93919fbc
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__categories.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/categories",
+        "isValid": true,
+        "attributes": {
+            "showPostCounts": false,
+            "displayAsDropdown": false,
+            "showHierarchy": false
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__categories.parsed.json b/tests/phpunit/data/blocks/fixtures/core__categories.parsed.json
new file mode 100644
index 0000000000..df39a8078d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__categories.parsed.json
@@ -0,0 +1,18 @@
+[
+    {
+        "blockName": "core/categories",
+        "attrs": {
+            "showPostCounts": false,
+            "displayAsDropdown": false,
+            "showHierarchy": false
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__categories.serialized.html b/tests/phpunit/data/blocks/fixtures/core__categories.serialized.html
new file mode 100644
index 0000000000..7816d6b192
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__categories.serialized.html
@@ -0,0 +1 @@
+<!-- wp:categories /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__code.html b/tests/phpunit/data/blocks/fixtures/core__code.html
new file mode 100644
index 0000000000..5d3f951c17
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__code.html
@@ -0,0 +1,5 @@
+<!-- wp:core/code -->
+<pre class="wp-block-code"><code>export default function MyButton() {
+	return &lt;Button&gt;Click Me!&lt;/Button&gt;;
+}</code></pre>
+<!-- /wp:core/code -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__code.json b/tests/phpunit/data/blocks/fixtures/core__code.json
new file mode 100644
index 0000000000..0958025736
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__code.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/code",
+        "isValid": true,
+        "attributes": {
+            "content": "export default function MyButton() {\n\treturn <Button>Click Me!</Button>;\n}"
+        },
+        "innerBlocks": [],
+        "originalContent": "<pre class=\"wp-block-code\"><code>export default function MyButton() {\n\treturn &lt;Button&gt;Click Me!&lt;/Button&gt;;\n}</code></pre>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__code.parsed.json b/tests/phpunit/data/blocks/fixtures/core__code.parsed.json
new file mode 100644
index 0000000000..5aea1d9a14
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__code.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/code",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<pre class=\"wp-block-code\"><code>export default function MyButton() {\n\treturn &lt;Button&gt;Click Me!&lt;/Button&gt;;\n}</code></pre>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__code.serialized.html b/tests/phpunit/data/blocks/fixtures/core__code.serialized.html
new file mode 100644
index 0000000000..651254a7ca
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__code.serialized.html
@@ -0,0 +1,5 @@
+<!-- wp:code -->
+<pre class="wp-block-code"><code>export default function MyButton() {
+	return &lt;Button>Click Me!&lt;/Button>;
+}</code></pre>
+<!-- /wp:code -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__column.html b/tests/phpunit/data/blocks/fixtures/core__column.html
new file mode 100644
index 0000000000..a18d2ee30a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__column.html
@@ -0,0 +1,10 @@
+<!-- wp:column -->
+<div class="wp-block-column">
+	<!-- wp:paragraph -->
+	<p>Column One, Paragraph One</p>
+	<!-- /wp:paragraph -->
+	<!-- wp:paragraph -->
+	<p>Column One, Paragraph Two</p>
+	<!-- /wp:paragraph -->
+</div>
+<!-- /wp:columns -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__column.json b/tests/phpunit/data/blocks/fixtures/core__column.json
new file mode 100644
index 0000000000..aabfc10300
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__column.json
@@ -0,0 +1,33 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/column",
+        "isValid": true,
+        "attributes": {},
+        "innerBlocks": [
+            {
+                "clientId": "_clientId_0",
+                "name": "core/paragraph",
+                "isValid": true,
+                "attributes": {
+                    "content": "Column One, Paragraph One",
+                    "dropCap": false
+                },
+                "innerBlocks": [],
+                "originalContent": "<p>Column One, Paragraph One</p>"
+            },
+            {
+                "clientId": "_clientId_1",
+                "name": "core/paragraph",
+                "isValid": true,
+                "attributes": {
+                    "content": "Column One, Paragraph Two",
+                    "dropCap": false
+                },
+                "innerBlocks": [],
+                "originalContent": "<p>Column One, Paragraph Two</p>"
+            }
+        ],
+        "originalContent": "<div class=\"wp-block-column\">\n\t\n\t\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__column.parsed.json b/tests/phpunit/data/blocks/fixtures/core__column.parsed.json
new file mode 100644
index 0000000000..74b53bdf6a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__column.parsed.json
@@ -0,0 +1,27 @@
+[
+    {
+        "blockName": "core/column",
+        "attrs": {},
+        "innerBlocks": [
+            {
+                "blockName": "core/paragraph",
+                "attrs": {},
+                "innerBlocks": [],
+                "innerHTML": "\n\t<p>Column One, Paragraph One</p>\n\t"
+            },
+            {
+                "blockName": "core/paragraph",
+                "attrs": {},
+                "innerBlocks": [],
+                "innerHTML": "\n\t<p>Column One, Paragraph Two</p>\n\t"
+            }
+        ],
+        "innerHTML": "\n<div class=\"wp-block-column\">\n\t\n\t\n</div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__column.serialized.html b/tests/phpunit/data/blocks/fixtures/core__column.serialized.html
new file mode 100644
index 0000000000..5d7839c470
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__column.serialized.html
@@ -0,0 +1,9 @@
+<!-- wp:column -->
+<div class="wp-block-column"><!-- wp:paragraph -->
+<p>Column One, Paragraph One</p>
+<!-- /wp:paragraph -->
+
+<!-- wp:paragraph -->
+<p>Column One, Paragraph Two</p>
+<!-- /wp:paragraph --></div>
+<!-- /wp:column -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__columns.html b/tests/phpunit/data/blocks/fixtures/core__columns.html
new file mode 100644
index 0000000000..bcced4e7b9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__columns.html
@@ -0,0 +1,24 @@
+<!-- wp:columns {"columns":3} -->
+<div class="wp-block-columns has-3-columns">
+	<!-- wp:column -->
+	<div class="wp-block-column">
+		<!-- wp:paragraph -->
+		<p>Column One, Paragraph One</p>
+		<!-- /wp:paragraph -->
+		<!-- wp:paragraph -->
+		<p>Column One, Paragraph Two</p>
+		<!-- /wp:paragraph -->
+	</div>
+	<!-- /wp:column -->
+	<!-- wp:column -->
+	<div class="wp-block-column">
+		<!-- wp:paragraph -->
+		<p>Column Two, Paragraph One</p>
+		<!-- /wp:paragraph -->
+		<!-- wp:paragraph -->
+		<p>Column Three, Paragraph One</p>
+		<!-- /wp:paragraph -->
+	</div>
+	<!-- /wp:column -->
+</div>
+<!-- /wp:columns -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__columns.json b/tests/phpunit/data/blocks/fixtures/core__columns.json
new file mode 100644
index 0000000000..2a446b72dc
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__columns.json
@@ -0,0 +1,75 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/columns",
+        "isValid": true,
+        "attributes": {
+            "columns": 3
+        },
+        "innerBlocks": [
+            {
+                "clientId": "_clientId_0",
+                "name": "core/column",
+                "isValid": true,
+                "attributes": {},
+                "innerBlocks": [
+                    {
+                        "clientId": "_clientId_0",
+                        "name": "core/paragraph",
+                        "isValid": true,
+                        "attributes": {
+                            "content": "Column One, Paragraph One",
+                            "dropCap": false
+                        },
+                        "innerBlocks": [],
+                        "originalContent": "<p>Column One, Paragraph One</p>"
+                    },
+                    {
+                        "clientId": "_clientId_1",
+                        "name": "core/paragraph",
+                        "isValid": true,
+                        "attributes": {
+                            "content": "Column One, Paragraph Two",
+                            "dropCap": false
+                        },
+                        "innerBlocks": [],
+                        "originalContent": "<p>Column One, Paragraph Two</p>"
+                    }
+                ],
+                "originalContent": "<div class=\"wp-block-column\">\n\t\t\n\t\t\n\t</div>"
+            },
+            {
+                "clientId": "_clientId_1",
+                "name": "core/column",
+                "isValid": true,
+                "attributes": {},
+                "innerBlocks": [
+                    {
+                        "clientId": "_clientId_0",
+                        "name": "core/paragraph",
+                        "isValid": true,
+                        "attributes": {
+                            "content": "Column Two, Paragraph One",
+                            "dropCap": false
+                        },
+                        "innerBlocks": [],
+                        "originalContent": "<p>Column Two, Paragraph One</p>"
+                    },
+                    {
+                        "clientId": "_clientId_1",
+                        "name": "core/paragraph",
+                        "isValid": true,
+                        "attributes": {
+                            "content": "Column Three, Paragraph One",
+                            "dropCap": false
+                        },
+                        "innerBlocks": [],
+                        "originalContent": "<p>Column Three, Paragraph One</p>"
+                    }
+                ],
+                "originalContent": "<div class=\"wp-block-column\">\n\t\t\n\t\t\n\t</div>"
+            }
+        ],
+        "originalContent": "<div class=\"wp-block-columns has-3-columns\">\n\t\n\t\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__columns.parsed.json b/tests/phpunit/data/blocks/fixtures/core__columns.parsed.json
new file mode 100644
index 0000000000..9ec5cef66a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__columns.parsed.json
@@ -0,0 +1,55 @@
+[
+    {
+        "blockName": "core/columns",
+        "attrs": {
+            "columns": 3
+        },
+        "innerBlocks": [
+            {
+                "blockName": "core/column",
+                "attrs": {},
+                "innerBlocks": [
+                    {
+                        "blockName": "core/paragraph",
+                        "attrs": {},
+                        "innerBlocks": [],
+                        "innerHTML": "\n\t\t<p>Column One, Paragraph One</p>\n\t\t"
+                    },
+                    {
+                        "blockName": "core/paragraph",
+                        "attrs": {},
+                        "innerBlocks": [],
+                        "innerHTML": "\n\t\t<p>Column One, Paragraph Two</p>\n\t\t"
+                    }
+                ],
+                "innerHTML": "\n\t<div class=\"wp-block-column\">\n\t\t\n\t\t\n\t</div>\n\t"
+            },
+            {
+                "blockName": "core/column",
+                "attrs": {},
+                "innerBlocks": [
+                    {
+                        "blockName": "core/paragraph",
+                        "attrs": {},
+                        "innerBlocks": [],
+                        "innerHTML": "\n\t\t<p>Column Two, Paragraph One</p>\n\t\t"
+                    },
+                    {
+                        "blockName": "core/paragraph",
+                        "attrs": {},
+                        "innerBlocks": [],
+                        "innerHTML": "\n\t\t<p>Column Three, Paragraph One</p>\n\t\t"
+                    }
+                ],
+                "innerHTML": "\n\t<div class=\"wp-block-column\">\n\t\t\n\t\t\n\t</div>\n\t"
+            }
+        ],
+        "innerHTML": "\n<div class=\"wp-block-columns has-3-columns\">\n\t\n\t\n</div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__columns.serialized.html b/tests/phpunit/data/blocks/fixtures/core__columns.serialized.html
new file mode 100644
index 0000000000..b7472ac094
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__columns.serialized.html
@@ -0,0 +1,21 @@
+<!-- wp:columns {"columns":3} -->
+<div class="wp-block-columns has-3-columns"><!-- wp:column -->
+<div class="wp-block-column"><!-- wp:paragraph -->
+<p>Column One, Paragraph One</p>
+<!-- /wp:paragraph -->
+
+<!-- wp:paragraph -->
+<p>Column One, Paragraph Two</p>
+<!-- /wp:paragraph --></div>
+<!-- /wp:column -->
+
+<!-- wp:column -->
+<div class="wp-block-column"><!-- wp:paragraph -->
+<p>Column Two, Paragraph One</p>
+<!-- /wp:paragraph -->
+
+<!-- wp:paragraph -->
+<p>Column Three, Paragraph One</p>
+<!-- /wp:paragraph --></div>
+<!-- /wp:column --></div>
+<!-- /wp:columns -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__cover-image.html b/tests/phpunit/data/blocks/fixtures/core__cover-image.html
new file mode 100644
index 0000000000..86b5915701
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__cover-image.html
@@ -0,0 +1,5 @@
+<!-- wp:core/cover-image {"url":"https://cldup.com/uuUqE_dXzy.jpg","dimRatio":40} -->
+<div class="wp-block-cover-image has-background-dim-40 has-background-dim" style="background-image:url(https://cldup.com/uuUqE_dXzy.jpg)">
+    <p class="wp-block-cover-image-text">Guten Berg!</p>
+</div>
+<!-- /wp:core/cover-image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__cover-image.json b/tests/phpunit/data/blocks/fixtures/core__cover-image.json
new file mode 100644
index 0000000000..342a160d3e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__cover-image.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/cover-image",
+        "isValid": true,
+        "attributes": {
+            "title": "Guten Berg!",
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "contentAlign": "center",
+            "hasParallax": false,
+            "dimRatio": 40
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-cover-image has-background-dim-40 has-background-dim\" style=\"background-image:url(https://cldup.com/uuUqE_dXzy.jpg)\">\n    <p class=\"wp-block-cover-image-text\">Guten Berg!</p>\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__cover-image.parsed.json b/tests/phpunit/data/blocks/fixtures/core__cover-image.parsed.json
new file mode 100644
index 0000000000..93bc4fbc8d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__cover-image.parsed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "blockName": "core/cover-image",
+        "attrs": {
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "dimRatio": 40
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-cover-image has-background-dim-40 has-background-dim\" style=\"background-image:url(https://cldup.com/uuUqE_dXzy.jpg)\">\n    <p class=\"wp-block-cover-image-text\">Guten Berg!</p>\n</div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__cover-image.serialized.html b/tests/phpunit/data/blocks/fixtures/core__cover-image.serialized.html
new file mode 100644
index 0000000000..d64692d60c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__cover-image.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:cover-image {"url":"https://cldup.com/uuUqE_dXzy.jpg","dimRatio":40} -->
+<div class="wp-block-cover-image has-background-dim-40 has-background-dim" style="background-image:url(https://cldup.com/uuUqE_dXzy.jpg)"><p class="wp-block-cover-image-text">Guten Berg!</p></div>
+<!-- /wp:cover-image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__embed.html b/tests/phpunit/data/blocks/fixtures/core__embed.html
new file mode 100644
index 0000000000..211e9e114e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__embed.html
@@ -0,0 +1,8 @@
+<!-- wp:core/embed {"url":"https://example.com/"} -->
+<figure class="wp-block-embed">
+    <div class="wp-block-embed__wrapper">
+        https://example.com/
+    </div>
+    <figcaption>Embedded content from an example URL</figcaption>
+</figure>
+<!-- /wp:core/embed -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__embed.json b/tests/phpunit/data/blocks/fixtures/core__embed.json
new file mode 100644
index 0000000000..916935db4c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__embed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/embed",
+        "isValid": true,
+        "attributes": {
+            "url": "https://example.com/",
+            "caption": "Embedded content from an example URL",
+            "allowResponsive": true
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-embed\">\n    <div class=\"wp-block-embed__wrapper\">\n        https://example.com/\n    </div>\n    <figcaption>Embedded content from an example URL</figcaption>\n</figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__embed.parsed.json b/tests/phpunit/data/blocks/fixtures/core__embed.parsed.json
new file mode 100644
index 0000000000..5efa23bb5f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__embed.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/embed",
+        "attrs": {
+            "url": "https://example.com/"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-embed\">\n    <div class=\"wp-block-embed__wrapper\">\n        https://example.com/\n    </div>\n    <figcaption>Embedded content from an example URL</figcaption>\n</figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__embed.serialized.html b/tests/phpunit/data/blocks/fixtures/core__embed.serialized.html
new file mode 100644
index 0000000000..3906dd45ee
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__embed.serialized.html
@@ -0,0 +1,5 @@
+<!-- wp:embed {"url":"https://example.com/"} -->
+<figure class="wp-block-embed"><div class="wp-block-embed__wrapper">
+https://example.com/
+</div><figcaption>Embedded content from an example URL</figcaption></figure>
+<!-- /wp:embed -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__new-window.html b/tests/phpunit/data/blocks/fixtures/core__file__new-window.html
new file mode 100644
index 0000000000..e8ee1b8258
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__new-window.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js","showDownloadButton":true,"id":176} -->
+<div class="wp-block-file"><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" target="_blank" rel="noreferrer noopener">6546</a><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" class="wp-block-file__button" download="6546">Download</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__new-window.json b/tests/phpunit/data/blocks/fixtures/core__file__new-window.json
new file mode 100644
index 0000000000..4922f02880
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__new-window.json
@@ -0,0 +1,18 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/file",
+        "isValid": true,
+        "attributes": {
+            "id": 176,
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "fileName": "6546",
+            "textLinkHref": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "textLinkTarget": "_blank",
+            "showDownloadButton": true,
+            "downloadButtonText": "Download"
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-file\"><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" target=\"_blank\" rel=\"noreferrer noopener\">6546</a><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" class=\"wp-block-file__button\" download=\"6546\">Download</a></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__new-window.parsed.json b/tests/phpunit/data/blocks/fixtures/core__file__new-window.parsed.json
new file mode 100644
index 0000000000..481c7e5c98
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__new-window.parsed.json
@@ -0,0 +1,18 @@
+[
+    {
+        "blockName": "core/file",
+        "attrs": {
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "showDownloadButton": true,
+            "id": 176
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-file\"><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" target=\"_blank\" rel=\"noreferrer noopener\">6546</a><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" class=\"wp-block-file__button\" download=\"6546\">Download</a></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__new-window.serialized.html b/tests/phpunit/data/blocks/fixtures/core__file__new-window.serialized.html
new file mode 100644
index 0000000000..7d28f4db58
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__new-window.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"id":176,"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js"} -->
+<div class="wp-block-file"><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" target="_blank" rel="noreferrer noopener">6546</a><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" class="wp-block-file__button" download="6546">Download</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.html b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.html
new file mode 100644
index 0000000000..54d82d4391
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js","showDownloadButton":false,"id":176} -->
+<div class="wp-block-file"><a href="http://localhost:8888/?attachment_id=176">lkjfijwef</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.json b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.json
new file mode 100644
index 0000000000..44ff5553ac
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.json
@@ -0,0 +1,17 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/file",
+        "isValid": true,
+        "attributes": {
+            "id": 176,
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "fileName": "lkjfijwef",
+            "textLinkHref": "http://localhost:8888/?attachment_id=176",
+            "showDownloadButton": false,
+            "downloadButtonText": ""
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-file\"><a href=\"http://localhost:8888/?attachment_id=176\">lkjfijwef</a></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.parsed.json b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.parsed.json
new file mode 100644
index 0000000000..65a2cffa5e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.parsed.json
@@ -0,0 +1,18 @@
+[
+    {
+        "blockName": "core/file",
+        "attrs": {
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "showDownloadButton": false,
+            "id": 176
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-file\"><a href=\"http://localhost:8888/?attachment_id=176\">lkjfijwef</a></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.serialized.html b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.serialized.html
new file mode 100644
index 0000000000..639e3e6c9d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-download-button.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"id":176,"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js","showDownloadButton":false} -->
+<div class="wp-block-file"><a href="http://localhost:8888/?attachment_id=176">lkjfijwef</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.html b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.html
new file mode 100644
index 0000000000..89c0390aac
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js","showDownloadButton":true,"id":176} -->
+<div class="wp-block-file"><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" class="wp-block-file__button" download="">Download</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.json b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.json
new file mode 100644
index 0000000000..6cf32d1f9d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/file",
+        "isValid": true,
+        "attributes": {
+            "id": 176,
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "fileName": "",
+            "showDownloadButton": true,
+            "downloadButtonText": "Download"
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-file\"><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" class=\"wp-block-file__button\" download=\"\">Download</a></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.parsed.json b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.parsed.json
new file mode 100644
index 0000000000..c905766eb9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.parsed.json
@@ -0,0 +1,18 @@
+[
+    {
+        "blockName": "core/file",
+        "attrs": {
+            "href": "http://localhost:8888/wp-content/uploads/2018/05/keycodes.js",
+            "showDownloadButton": true,
+            "id": 176
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-file\"><a href=\"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js\" class=\"wp-block-file__button\" download=\"\">Download</a></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.serialized.html b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.serialized.html
new file mode 100644
index 0000000000..a0ab5b5f41
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__file__no-text-link.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:file {"id":176,"href":"http://localhost:8888/wp-content/uploads/2018/05/keycodes.js"} -->
+<div class="wp-block-file"><a href="http://localhost:8888/wp-content/uploads/2018/05/keycodes.js" class="wp-block-file__button" download="">Download</a></div>
+<!-- /wp:file -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform.html b/tests/phpunit/data/blocks/fixtures/core__freeform.html
new file mode 100644
index 0000000000..302e94487b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform.html
@@ -0,0 +1,6 @@
+<!-- wp:core/freeform -->
+Testing freeform block with some
+<div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
+<!-- /wp:core/freeform -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform.json b/tests/phpunit/data/blocks/fixtures/core__freeform.json
new file mode 100644
index 0000000000..72341f093f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<p>Testing freeform block with some\n</p><div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<p>Testing freeform block with some\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform.parsed.json b/tests/phpunit/data/blocks/fixtures/core__freeform.parsed.json
new file mode 100644
index 0000000000..5cf330c0e9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/freeform",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\nTesting freeform block with some\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform.serialized.html b/tests/phpunit/data/blocks/fixtures/core__freeform.serialized.html
new file mode 100644
index 0000000000..4fed04550b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform.serialized.html
@@ -0,0 +1,4 @@
+<p>Testing freeform block with some
+</p><div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.html b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.html
new file mode 100644
index 0000000000..2c349303c5
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.html
@@ -0,0 +1,4 @@
+Testing freeform block with some
+<div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.json b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.json
new file mode 100644
index 0000000000..72341f093f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<p>Testing freeform block with some\n</p><div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<p>Testing freeform block with some\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.parsed.json b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.parsed.json
new file mode 100644
index 0000000000..e0b2c76f29
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.parsed.json
@@ -0,0 +1,8 @@
+[
+    {
+        "attrs": {},
+        "blockName": null,
+        "innerBlocks": [],
+        "innerHTML": "Testing freeform block with some\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.serialized.html b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.serialized.html
new file mode 100644
index 0000000000..4fed04550b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__freeform__undelimited.serialized.html
@@ -0,0 +1,4 @@
+<p>Testing freeform block with some
+</p><div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery.html b/tests/phpunit/data/blocks/fixtures/core__gallery.html
new file mode 100644
index 0000000000..5e48c7e663
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery.html
@@ -0,0 +1,14 @@
+<!-- wp:core/gallery -->
+<ul class="wp-block-gallery columns-2 is-cropped">
+	<li class="blocks-gallery-item">
+		<figure>
+			<img src="https://cldup.com/uuUqE_dXzy.jpg" alt="title" />
+		</figure>
+	</li>
+	<li class="blocks-gallery-item">
+		<figure>
+			<img src="http://google.com/hi.png" alt="title" />
+		</figure>
+	</li>
+</ul>
+<!-- /wp:core/gallery -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery.json b/tests/phpunit/data/blocks/fixtures/core__gallery.json
new file mode 100644
index 0000000000..8cfcc26d3b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery.json
@@ -0,0 +1,25 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/gallery",
+        "isValid": true,
+        "attributes": {
+            "images": [
+                {
+                    "url": "https://cldup.com/uuUqE_dXzy.jpg",
+                    "alt": "title",
+                    "caption": ""
+                },
+                {
+                    "url": "http://google.com/hi.png",
+                    "alt": "title",
+                    "caption": ""
+                }
+            ],
+            "imageCrop": true,
+            "linkTo": "none"
+        },
+        "innerBlocks": [],
+        "originalContent": "<ul class=\"wp-block-gallery columns-2 is-cropped\">\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"http://google.com/hi.png\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n</ul>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery.parsed.json b/tests/phpunit/data/blocks/fixtures/core__gallery.parsed.json
new file mode 100644
index 0000000000..3d80657c7f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/gallery",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<ul class=\"wp-block-gallery columns-2 is-cropped\">\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"http://google.com/hi.png\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n</ul>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery.serialized.html b/tests/phpunit/data/blocks/fixtures/core__gallery.serialized.html
new file mode 100644
index 0000000000..5bf6ce819f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:gallery -->
+<ul class="wp-block-gallery columns-2 is-cropped"><li class="blocks-gallery-item"><figure><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="title"/></figure></li><li class="blocks-gallery-item"><figure><img src="http://google.com/hi.png" alt="title"/></figure></li></ul>
+<!-- /wp:gallery -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery__columns.html b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.html
new file mode 100644
index 0000000000..cf1f1bb43f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.html
@@ -0,0 +1,14 @@
+<!-- wp:core/gallery {"columns":1} -->
+<ul class="wp-block-gallery columns-1 is-cropped">
+	<li class="blocks-gallery-item">
+		<figure>
+			<img src="https://cldup.com/uuUqE_dXzy.jpg" alt="title" />
+		</figure>
+	</li>
+	<li class="blocks-gallery-item">
+		<figure>
+			<img src="http://google.com/hi.png" alt="title" />
+		</figure>
+	</li>
+</ul>
+<!-- /wp:core/gallery -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery__columns.json b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.json
new file mode 100644
index 0000000000..b3daaa05f6
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.json
@@ -0,0 +1,26 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/gallery",
+        "isValid": true,
+        "attributes": {
+            "images": [
+                {
+                    "url": "https://cldup.com/uuUqE_dXzy.jpg",
+                    "alt": "title",
+                    "caption": ""
+                },
+                {
+                    "url": "http://google.com/hi.png",
+                    "alt": "title",
+                    "caption": ""
+                }
+            ],
+            "columns": 1,
+            "imageCrop": true,
+            "linkTo": "none"
+        },
+        "innerBlocks": [],
+        "originalContent": "<ul class=\"wp-block-gallery columns-1 is-cropped\">\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"http://google.com/hi.png\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n</ul>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery__columns.parsed.json b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.parsed.json
new file mode 100644
index 0000000000..44faed907a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/gallery",
+        "attrs": {
+            "columns": 1
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<ul class=\"wp-block-gallery columns-1 is-cropped\">\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n\t<li class=\"blocks-gallery-item\">\n\t\t<figure>\n\t\t\t<img src=\"http://google.com/hi.png\" alt=\"title\" />\n\t\t</figure>\n\t</li>\n</ul>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__gallery__columns.serialized.html b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.serialized.html
new file mode 100644
index 0000000000..183e484ec4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__gallery__columns.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:gallery {"columns":1} -->
+<ul class="wp-block-gallery columns-1 is-cropped"><li class="blocks-gallery-item"><figure><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="title"/></figure></li><li class="blocks-gallery-item"><figure><img src="http://google.com/hi.png" alt="title"/></figure></li></ul>
+<!-- /wp:gallery -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.html b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.html
new file mode 100644
index 0000000000..7755d1dcf4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.html
@@ -0,0 +1,3 @@
+<!-- wp:core/heading -->
+<h2>The <em>Inserter</em> Tool</h2>
+<!-- /wp:core/heading -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.json b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.json
new file mode 100644
index 0000000000..b72785dd6d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/heading",
+        "isValid": true,
+        "attributes": {
+            "content": "The <em>Inserter</em> Tool",
+            "level": 2
+        },
+        "innerBlocks": [],
+        "originalContent": "<h2>The <em>Inserter</em> Tool</h2>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.parsed.json b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.parsed.json
new file mode 100644
index 0000000000..76d235d42c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/heading",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<h2>The <em>Inserter</em> Tool</h2>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.serialized.html b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.serialized.html
new file mode 100644
index 0000000000..55ce73502b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2-em.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:heading -->
+<h2>The <em>Inserter</em> Tool</h2>
+<!-- /wp:heading -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2.html b/tests/phpunit/data/blocks/fixtures/core__heading__h2.html
new file mode 100644
index 0000000000..a55b391a25
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2.html
@@ -0,0 +1,3 @@
+<!-- wp:core/heading -->
+<h2>A picture is worth a thousand words, or so the saying goes</h2>
+<!-- /wp:core/heading -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2.json b/tests/phpunit/data/blocks/fixtures/core__heading__h2.json
new file mode 100644
index 0000000000..f2073ff78b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/heading",
+        "isValid": true,
+        "attributes": {
+            "content": "A picture is worth a thousand words, or so the saying goes",
+            "level": 2
+        },
+        "innerBlocks": [],
+        "originalContent": "<h2>A picture is worth a thousand words, or so the saying goes</h2>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2.parsed.json b/tests/phpunit/data/blocks/fixtures/core__heading__h2.parsed.json
new file mode 100644
index 0000000000..700f5f941e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/heading",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<h2>A picture is worth a thousand words, or so the saying goes</h2>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__heading__h2.serialized.html b/tests/phpunit/data/blocks/fixtures/core__heading__h2.serialized.html
new file mode 100644
index 0000000000..1212bf83c3
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__heading__h2.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:heading -->
+<h2>A picture is worth a thousand words, or so the saying goes</h2>
+<!-- /wp:heading -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__html.html b/tests/phpunit/data/blocks/fixtures/core__html.html
new file mode 100644
index 0000000000..4824e6e373
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__html.html
@@ -0,0 +1,4 @@
+<!-- wp:core/html -->
+<h1>Some HTML code</h1>
+<marquee>This text will scroll from right to left</marquee>
+<!-- /wp:core/html -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__html.json b/tests/phpunit/data/blocks/fixtures/core__html.json
new file mode 100644
index 0000000000..cd7cf91f03
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__html.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/html",
+        "isValid": true,
+        "attributes": {
+            "content": "<h1>Some HTML code</h1>\n<marquee>This text will scroll from right to left</marquee>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<h1>Some HTML code</h1>\n<marquee>This text will scroll from right to left</marquee>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__html.parsed.json b/tests/phpunit/data/blocks/fixtures/core__html.parsed.json
new file mode 100644
index 0000000000..2bfdc65866
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__html.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/html",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<h1>Some HTML code</h1>\n<marquee>This text will scroll from right to left</marquee>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__html.serialized.html b/tests/phpunit/data/blocks/fixtures/core__html.serialized.html
new file mode 100644
index 0000000000..8abffc385d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__html.serialized.html
@@ -0,0 +1,4 @@
+<!-- wp:html -->
+<h1>Some HTML code</h1>
+<marquee>This text will scroll from right to left</marquee>
+<!-- /wp:html -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image.html b/tests/phpunit/data/blocks/fixtures/core__image.html
new file mode 100644
index 0000000000..eda663561a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image.html
@@ -0,0 +1,3 @@
+<!-- wp:core/image -->
+<figure class="wp-block-image"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="" /></figure>
+<!-- /wp:core/image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image.json b/tests/phpunit/data/blocks/fixtures/core__image.json
new file mode 100644
index 0000000000..4369150f0c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image.json
@@ -0,0 +1,15 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/image",
+        "isValid": true,
+        "attributes": {
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "alt": "",
+            "caption": "",
+            "linkDestination": "none"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-image\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image.parsed.json b/tests/phpunit/data/blocks/fixtures/core__image.parsed.json
new file mode 100644
index 0000000000..fff414d9b0
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/image",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-image\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image.serialized.html b/tests/phpunit/data/blocks/fixtures/core__image.serialized.html
new file mode 100644
index 0000000000..5dfb0bac3e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:image -->
+<figure class="wp-block-image"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt=""/></figure>
+<!-- /wp:image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.html b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.html
new file mode 100644
index 0000000000..908250d8ca
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.html
@@ -0,0 +1,3 @@
+<!-- wp:core/image {"linkDestination":"attachment"}  -->
+<figure class="wp-block-image"><a href="http://localhost:8888/?attachment_id=7"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="" /></a></figure>
+<!-- /wp:core/image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.json b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.json
new file mode 100644
index 0000000000..5d16958904
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/image",
+        "isValid": true,
+        "attributes": {
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "alt": "",
+            "caption": "",
+            "href": "http://localhost:8888/?attachment_id=7",
+            "linkDestination": "attachment"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-image\"><a href=\"http://localhost:8888/?attachment_id=7\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.parsed.json b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.parsed.json
new file mode 100644
index 0000000000..e5da07242d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/image",
+        "attrs": {
+            "linkDestination": "attachment"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-image\"><a href=\"http://localhost:8888/?attachment_id=7\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.serialized.html b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.serialized.html
new file mode 100644
index 0000000000..f5ebb9af41
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__attachment-link.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:image {"linkDestination":"attachment"} -->
+<figure class="wp-block-image"><a href="http://localhost:8888/?attachment_id=7"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt=""/></a></figure>
+<!-- /wp:image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__center-caption.html b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.html
new file mode 100644
index 0000000000..bfe40d190f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.html
@@ -0,0 +1,3 @@
+<!-- wp:core/image {"align":"center"} -->
+<div class="wp-block-image"><figure class="aligncenter"><img src="https://cldup.com/YLYhpou2oq.jpg" alt="" /><figcaption>Give it a try. Press the &quot;really wide&quot; button on the image toolbar.</figcaption></figure></div>
+<!-- /wp:core/image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__center-caption.json b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.json
new file mode 100644
index 0000000000..f569bda22c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/image",
+        "isValid": true,
+        "attributes": {
+            "url": "https://cldup.com/YLYhpou2oq.jpg",
+            "alt": "",
+            "caption": "Give it a try. Press the \"really wide\" button on the image toolbar.",
+            "align": "center",
+            "linkDestination": "none"
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img src=\"https://cldup.com/YLYhpou2oq.jpg\" alt=\"\" /><figcaption>Give it a try. Press the &quot;really wide&quot; button on the image toolbar.</figcaption></figure></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__center-caption.parsed.json b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.parsed.json
new file mode 100644
index 0000000000..290057c287
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/image",
+        "attrs": {
+            "align": "center"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-image\"><figure class=\"aligncenter\"><img src=\"https://cldup.com/YLYhpou2oq.jpg\" alt=\"\" /><figcaption>Give it a try. Press the &quot;really wide&quot; button on the image toolbar.</figcaption></figure></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__center-caption.serialized.html b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.serialized.html
new file mode 100644
index 0000000000..3410b04fdf
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__center-caption.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:image {"align":"center"} -->
+<div class="wp-block-image"><figure class="aligncenter"><img src="https://cldup.com/YLYhpou2oq.jpg" alt=""/><figcaption>Give it a try. Press the "really wide" button on the image toolbar.</figcaption></figure></div>
+<!-- /wp:image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__custom-link.html b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.html
new file mode 100644
index 0000000000..353dc5376b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.html
@@ -0,0 +1,3 @@
+<!-- wp:core/image {"linkDestination":"custom"}  -->
+<figure class="wp-block-image"><a href="https://wordpress.org/"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="" /></a></figure>
+<!-- /wp:core/image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__custom-link.json b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.json
new file mode 100644
index 0000000000..735e552282
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/image",
+        "isValid": true,
+        "attributes": {
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "alt": "",
+            "caption": "",
+            "href": "https://wordpress.org/",
+            "linkDestination": "custom"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-image\"><a href=\"https://wordpress.org/\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__custom-link.parsed.json b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.parsed.json
new file mode 100644
index 0000000000..d814737aae
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/image",
+        "attrs": {
+            "linkDestination": "custom"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-image\"><a href=\"https://wordpress.org/\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__custom-link.serialized.html b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.serialized.html
new file mode 100644
index 0000000000..47357bea6b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__custom-link.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:image {"linkDestination":"custom"} -->
+<figure class="wp-block-image"><a href="https://wordpress.org/"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt=""/></a></figure>
+<!-- /wp:image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__media-link.html b/tests/phpunit/data/blocks/fixtures/core__image__media-link.html
new file mode 100644
index 0000000000..90b3d22711
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__media-link.html
@@ -0,0 +1,3 @@
+<!-- wp:core/image {"linkDestination":"media"}  -->
+<figure class="wp-block-image"><a href="https://cldup.com/uuUqE_dXzy.jpg"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt="" /></a></figure>
+<!-- /wp:core/image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__media-link.json b/tests/phpunit/data/blocks/fixtures/core__image__media-link.json
new file mode 100644
index 0000000000..690fa778b6
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__media-link.json
@@ -0,0 +1,16 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/image",
+        "isValid": true,
+        "attributes": {
+            "url": "https://cldup.com/uuUqE_dXzy.jpg",
+            "alt": "",
+            "caption": "",
+            "href": "https://cldup.com/uuUqE_dXzy.jpg",
+            "linkDestination": "media"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-image\"><a href=\"https://cldup.com/uuUqE_dXzy.jpg\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__media-link.parsed.json b/tests/phpunit/data/blocks/fixtures/core__image__media-link.parsed.json
new file mode 100644
index 0000000000..345c5d4e25
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__media-link.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/image",
+        "attrs": {
+            "linkDestination": "media"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-image\"><a href=\"https://cldup.com/uuUqE_dXzy.jpg\"><img src=\"https://cldup.com/uuUqE_dXzy.jpg\" alt=\"\" /></a></figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__image__media-link.serialized.html b/tests/phpunit/data/blocks/fixtures/core__image__media-link.serialized.html
new file mode 100644
index 0000000000..721abac903
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__image__media-link.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:image {"linkDestination":"media"} -->
+<figure class="wp-block-image"><a href="https://cldup.com/uuUqE_dXzy.jpg"><img src="https://cldup.com/uuUqE_dXzy.jpg" alt=""/></a></figure>
+<!-- /wp:image -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.html b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.html
new file mode 100644
index 0000000000..1eaeb57026
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.html
@@ -0,0 +1 @@
+<!-- wp:core/invalid-Capitals /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.json b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.json
new file mode 100644
index 0000000000..91dc39fca8
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<p><!-- wp:core/invalid-Capitals /--></p>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<p><!-- wp:core/invalid-Capitals /--></p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.parsed.json b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.parsed.json
new file mode 100644
index 0000000000..c17c81b398
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.parsed.json
@@ -0,0 +1,8 @@
+[
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "<!-- wp:core/invalid-Capitals /-->\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.serialized.html b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.serialized.html
new file mode 100644
index 0000000000..4b0ff53da7
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-Capitals.serialized.html
@@ -0,0 +1 @@
+<p><!-- wp:core/invalid-Capitals /--></p>
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-special.html b/tests/phpunit/data/blocks/fixtures/core__invalid-special.html
new file mode 100644
index 0000000000..548aef63c7
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-special.html
@@ -0,0 +1 @@
+<!-- wp:core/invalid-$special /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-special.json b/tests/phpunit/data/blocks/fixtures/core__invalid-special.json
new file mode 100644
index 0000000000..cd026a2a3c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-special.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<p><!-- wp:core/invalid-$special /--></p>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<p><!-- wp:core/invalid-$special /--></p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-special.parsed.json b/tests/phpunit/data/blocks/fixtures/core__invalid-special.parsed.json
new file mode 100644
index 0000000000..3198b43be5
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-special.parsed.json
@@ -0,0 +1,8 @@
+[
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "<!-- wp:core/invalid-$special /-->\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__invalid-special.serialized.html b/tests/phpunit/data/blocks/fixtures/core__invalid-special.serialized.html
new file mode 100644
index 0000000000..de4f2acc41
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__invalid-special.serialized.html
@@ -0,0 +1 @@
+<p><!-- wp:core/invalid-$special /--></p>
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-comments.html b/tests/phpunit/data/blocks/fixtures/core__latest-comments.html
new file mode 100644
index 0000000000..cc4a2523b9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-comments.html
@@ -0,0 +1 @@
+<!-- wp:latest-comments {"displayAvatar":true,"displayExcerpt":true,"displayTimestamp":true} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-comments.json b/tests/phpunit/data/blocks/fixtures/core__latest-comments.json
new file mode 100644
index 0000000000..a455877276
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-comments.json
@@ -0,0 +1,15 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/latest-comments",
+        "isValid": true,
+        "attributes": {
+            "commentsToShow": 5,
+            "displayAvatar": true,
+            "displayDate": true,
+            "displayExcerpt": true
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-comments.parsed.json b/tests/phpunit/data/blocks/fixtures/core__latest-comments.parsed.json
new file mode 100644
index 0000000000..7e8bb541ad
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-comments.parsed.json
@@ -0,0 +1,18 @@
+[
+    {
+        "blockName": "core/latest-comments",
+        "attrs": {
+            "displayAvatar": true,
+            "displayExcerpt": true,
+            "displayTimestamp": true
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-comments.serialized.html b/tests/phpunit/data/blocks/fixtures/core__latest-comments.serialized.html
new file mode 100644
index 0000000000..a50d5664a6
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-comments.serialized.html
@@ -0,0 +1 @@
+<!-- wp:latest-comments /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts.html b/tests/phpunit/data/blocks/fixtures/core__latest-posts.html
new file mode 100644
index 0000000000..99d215f58a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts.html
@@ -0,0 +1 @@
+<!-- wp:core/latest-posts {"postsToShow":5,"displayPostDate":false} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts.json b/tests/phpunit/data/blocks/fixtures/core__latest-posts.json
new file mode 100644
index 0000000000..f31c903f58
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts.json
@@ -0,0 +1,17 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/latest-posts",
+        "isValid": true,
+        "attributes": {
+            "postsToShow": 5,
+            "displayPostDate": false,
+            "postLayout": "list",
+            "columns": 3,
+            "order": "desc",
+            "orderBy": "date"
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts.parsed.json b/tests/phpunit/data/blocks/fixtures/core__latest-posts.parsed.json
new file mode 100644
index 0000000000..f1c800291d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts.parsed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "blockName": "core/latest-posts",
+        "attrs": {
+            "postsToShow": 5,
+            "displayPostDate": false
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts.serialized.html b/tests/phpunit/data/blocks/fixtures/core__latest-posts.serialized.html
new file mode 100644
index 0000000000..2c5b3f264c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts.serialized.html
@@ -0,0 +1 @@
+<!-- wp:latest-posts /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.html b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.html
new file mode 100644
index 0000000000..d3128a6682
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.html
@@ -0,0 +1 @@
+<!-- wp:core/latest-posts {"postsToShow":5,"displayPostDate":true} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.json b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.json
new file mode 100644
index 0000000000..024e1a7f37
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.json
@@ -0,0 +1,17 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/latest-posts",
+        "isValid": true,
+        "attributes": {
+            "postsToShow": 5,
+            "displayPostDate": true,
+            "postLayout": "list",
+            "columns": 3,
+            "order": "desc",
+            "orderBy": "date"
+        },
+        "innerBlocks": [],
+        "originalContent": ""
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.parsed.json b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.parsed.json
new file mode 100644
index 0000000000..a92b392679
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.parsed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "blockName": "core/latest-posts",
+        "attrs": {
+            "postsToShow": 5,
+            "displayPostDate": true
+        },
+        "innerBlocks": [],
+        "innerHTML": ""
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.serialized.html b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.serialized.html
new file mode 100644
index 0000000000..0d80d351d6
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__latest-posts__displayPostDate.serialized.html
@@ -0,0 +1 @@
+<!-- wp:latest-posts {"displayPostDate":true} /-->
diff --git a/tests/phpunit/data/blocks/fixtures/core__list__ul.html b/tests/phpunit/data/blocks/fixtures/core__list__ul.html
new file mode 100644
index 0000000000..aef6bf669f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__list__ul.html
@@ -0,0 +1,3 @@
+<!-- wp:core/list -->
+<ul><li>Text & Headings</li><li>Images & Videos</li><li>Galleries</li><li>Embeds, like YouTube, Tweets, or other WordPress posts.</li><li>Layout blocks, like Buttons, Hero Images, Separators, etc.</li><li>And <em>Lists</em> like this one of course :)</li></ul>
+<!-- /wp:core/list -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__list__ul.json b/tests/phpunit/data/blocks/fixtures/core__list__ul.json
new file mode 100644
index 0000000000..17baec7cef
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__list__ul.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/list",
+        "isValid": true,
+        "attributes": {
+            "ordered": false,
+            "values": "<li>Text &amp; Headings</li><li>Images &amp; Videos</li><li>Galleries</li><li>Embeds, like YouTube, Tweets, or other WordPress posts.</li><li>Layout blocks, like Buttons, Hero Images, Separators, etc.</li><li>And <em>Lists</em> like this one of course :)</li>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<ul><li>Text & Headings</li><li>Images & Videos</li><li>Galleries</li><li>Embeds, like YouTube, Tweets, or other WordPress posts.</li><li>Layout blocks, like Buttons, Hero Images, Separators, etc.</li><li>And <em>Lists</em> like this one of course :)</li></ul>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__list__ul.parsed.json b/tests/phpunit/data/blocks/fixtures/core__list__ul.parsed.json
new file mode 100644
index 0000000000..c42181ba55
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__list__ul.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/list",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<ul><li>Text & Headings</li><li>Images & Videos</li><li>Galleries</li><li>Embeds, like YouTube, Tweets, or other WordPress posts.</li><li>Layout blocks, like Buttons, Hero Images, Separators, etc.</li><li>And <em>Lists</em> like this one of course :)</li></ul>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__list__ul.serialized.html b/tests/phpunit/data/blocks/fixtures/core__list__ul.serialized.html
new file mode 100644
index 0000000000..6b83b73a47
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__list__ul.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:list -->
+<ul><li>Text &amp; Headings</li><li>Images &amp; Videos</li><li>Galleries</li><li>Embeds, like YouTube, Tweets, or other WordPress posts.</li><li>Layout blocks, like Buttons, Hero Images, Separators, etc.</li><li>And <em>Lists</em> like this one of course :)</li></ul>
+<!-- /wp:list -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__missing.html b/tests/phpunit/data/blocks/fixtures/core__missing.html
new file mode 100644
index 0000000000..a29cbdea3f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__missing.html
@@ -0,0 +1,6 @@
+<!-- wp:unregistered/example {"attr1":"One","attr2":"Two"} -->
+<p>Testing missing block with some</p>
+<div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
+<!-- /wp:unregistered/example -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__missing.json b/tests/phpunit/data/blocks/fixtures/core__missing.json
new file mode 100644
index 0000000000..4e90cf7132
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__missing.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/missing",
+        "isValid": true,
+        "attributes": {
+			"originalContent": "<!-- wp:unregistered/example {\"attr1\":\"One\",\"attr2\":\"Two\"} -->\n<p>Testing missing block with some</p>\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>\n<!-- /wp:unregistered/example -->",
+			"originalName": "unregistered/example",
+			"originalUndelimitedContent": "<p>Testing missing block with some</p>\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>"
+        },
+        "innerBlocks": [],
+        "originalContent": "<!-- wp:unregistered/example {\"attr1\":\"One\",\"attr2\":\"Two\"} -->\n<p>Testing missing block with some</p>\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>\n<!-- /wp:unregistered/example -->"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__missing.parsed.json b/tests/phpunit/data/blocks/fixtures/core__missing.parsed.json
new file mode 100644
index 0000000000..3466b8cf2a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__missing.parsed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "blockName": "unregistered/example",
+        "attrs": {
+			"attr1": "One",
+			"attr2": "Two"
+		},
+        "innerBlocks": [],
+        "innerHTML": "\n<p>Testing missing block with some</p>\n<div class=\"wp-some-class\">\n\tHTML <span style=\"color: red;\">content</span>\n</div>\n"
+    },
+    {
+		"blockName": null,
+		"attrs": {},
+		"innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__missing.serialized.html b/tests/phpunit/data/blocks/fixtures/core__missing.serialized.html
new file mode 100644
index 0000000000..a29cbdea3f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__missing.serialized.html
@@ -0,0 +1,6 @@
+<!-- wp:unregistered/example {"attr1":"One","attr2":"Two"} -->
+<p>Testing missing block with some</p>
+<div class="wp-some-class">
+	HTML <span style="color: red;">content</span>
+</div>
+<!-- /wp:unregistered/example -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__more.html b/tests/phpunit/data/blocks/fixtures/core__more.html
new file mode 100644
index 0000000000..b3b4f9e5e4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more.html
@@ -0,0 +1,3 @@
+<!-- wp:core/more -->
+<!--more-->
+<!-- /wp:core/more -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__more.json b/tests/phpunit/data/blocks/fixtures/core__more.json
new file mode 100644
index 0000000000..886638ab06
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/more",
+        "isValid": true,
+        "attributes": {
+            "noTeaser": false
+        },
+        "innerBlocks": [],
+        "originalContent": "<!--more-->"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__more.parsed.json b/tests/phpunit/data/blocks/fixtures/core__more.parsed.json
new file mode 100644
index 0000000000..176e7fe7f7
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/more",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<!--more-->\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__more.serialized.html b/tests/phpunit/data/blocks/fixtures/core__more.serialized.html
new file mode 100644
index 0000000000..3b02c97e91
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:more -->
+<!--more-->
+<!-- /wp:more -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.html b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.html
new file mode 100644
index 0000000000..1dcca90966
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.html
@@ -0,0 +1,4 @@
+<!-- wp:core/more {"customText":"Continue Reading","noTeaser":true} -->
+<!--more Continue Reading-->
+<!--noteaser-->
+<!-- /wp:core/more -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.json b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.json
new file mode 100644
index 0000000000..7f7811e0d1
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/more",
+        "isValid": true,
+        "attributes": {
+            "customText": "Continue Reading",
+            "noTeaser": true
+        },
+        "innerBlocks": [],
+        "originalContent": "<!--more Continue Reading-->\n<!--noteaser-->"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.parsed.json b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.parsed.json
new file mode 100644
index 0000000000..a533e3c09c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.parsed.json
@@ -0,0 +1,17 @@
+[
+    {
+        "blockName": "core/more",
+        "attrs": {
+            "customText": "Continue Reading",
+            "noTeaser": true
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<!--more Continue Reading-->\n<!--noteaser-->\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.serialized.html b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.serialized.html
new file mode 100644
index 0000000000..6cc18dcfba
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__more__custom-text-teaser.serialized.html
@@ -0,0 +1,4 @@
+<!-- wp:more {"customText":"Continue Reading","noTeaser":true} -->
+<!--more Continue Reading-->
+<!--noteaser-->
+<!-- /wp:more -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__nextpage.html b/tests/phpunit/data/blocks/fixtures/core__nextpage.html
new file mode 100644
index 0000000000..9bf78b8cbf
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__nextpage.html
@@ -0,0 +1,3 @@
+<!-- wp:core/nextpage -->
+<!--nextpage-->
+<!-- /wp:core/nextpage -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__nextpage.json b/tests/phpunit/data/blocks/fixtures/core__nextpage.json
new file mode 100644
index 0000000000..1a2c5478ae
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__nextpage.json
@@ -0,0 +1,10 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/nextpage",
+        "isValid": true,
+        "attributes": {},
+        "innerBlocks": [],
+        "originalContent": "<!--nextpage-->"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__nextpage.parsed.json b/tests/phpunit/data/blocks/fixtures/core__nextpage.parsed.json
new file mode 100644
index 0000000000..e4dd2534c8
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__nextpage.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/nextpage",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<!--nextpage-->\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__nextpage.serialized.html b/tests/phpunit/data/blocks/fixtures/core__nextpage.serialized.html
new file mode 100644
index 0000000000..beef64ebd5
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__nextpage.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:nextpage -->
+<!--nextpage-->
+<!-- /wp:nextpage -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.html b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.html
new file mode 100644
index 0000000000..d41481a57f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.html
@@ -0,0 +1,3 @@
+<!-- wp:core/paragraph {"align":"right"} -->
+<p style="text-align:right;">... like this one, which is separate from the above and right aligned.</p>
+<!-- /wp:core/paragraph -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.json b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.json
new file mode 100644
index 0000000000..079d9a704f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/paragraph",
+        "isValid": true,
+        "attributes": {
+            "content": "... like this one, which is separate from the above and right aligned.",
+            "align": "right",
+            "dropCap": false
+        },
+        "innerBlocks": [],
+        "originalContent": "<p style=\"text-align:right;\">... like this one, which is separate from the above and right aligned.</p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.parsed.json b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.parsed.json
new file mode 100644
index 0000000000..060d40a38d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/paragraph",
+        "attrs": {
+            "align": "right"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<p style=\"text-align:right;\">... like this one, which is separate from the above and right aligned.</p>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.serialized.html b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.serialized.html
new file mode 100644
index 0000000000..3e18265b5c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__align-right.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph {"align":"right"} -->
+<p style="text-align:right">... like this one, which is separate from the above and right aligned.</p>
+<!-- /wp:paragraph -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.html b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.html
new file mode 100644
index 0000000000..96ec545b64
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+Unwrapped is <em>still</em> valid.
+<!-- /wp:paragraph -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.json b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.json
new file mode 100644
index 0000000000..ce0f468e35
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/paragraph",
+        "isValid": true,
+        "attributes": {
+            "content": "Unwrapped is <em>still</em> valid.",
+            "dropCap": false
+        },
+        "innerBlocks": [],
+        "originalContent": "Unwrapped is <em>still</em> valid."
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.parsed.json b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.parsed.json
new file mode 100644
index 0000000000..ac11af1b3a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/paragraph",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\nUnwrapped is <em>still</em> valid.\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.serialized.html b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.serialized.html
new file mode 100644
index 0000000000..ddc0a9d9a1
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__paragraph__deprecated.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>Unwrapped is <em>still</em> valid.</p>
+<!-- /wp:paragraph -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__preformatted.html b/tests/phpunit/data/blocks/fixtures/core__preformatted.html
new file mode 100644
index 0000000000..1a890a7a5d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__preformatted.html
@@ -0,0 +1,3 @@
+<!-- wp:core/preformatted -->
+<pre class="wp-block-preformatted">Some <em>preformatted</em> text...<br>And more!</pre>
+<!-- /wp:core/preformatted -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__preformatted.json b/tests/phpunit/data/blocks/fixtures/core__preformatted.json
new file mode 100644
index 0000000000..290c7e9849
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__preformatted.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/preformatted",
+        "isValid": true,
+        "attributes": {
+            "content": "Some <em>preformatted</em> text...<br>And more!"
+        },
+        "innerBlocks": [],
+        "originalContent": "<pre class=\"wp-block-preformatted\">Some <em>preformatted</em> text...<br>And more!</pre>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__preformatted.parsed.json b/tests/phpunit/data/blocks/fixtures/core__preformatted.parsed.json
new file mode 100644
index 0000000000..247fdda2e3
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__preformatted.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/preformatted",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<pre class=\"wp-block-preformatted\">Some <em>preformatted</em> text...<br>And more!</pre>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__preformatted.serialized.html b/tests/phpunit/data/blocks/fixtures/core__preformatted.serialized.html
new file mode 100644
index 0000000000..8c7cf539e4
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__preformatted.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:preformatted -->
+<pre class="wp-block-preformatted">Some <em>preformatted</em> text...<br>And more!</pre>
+<!-- /wp:preformatted -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote.html b/tests/phpunit/data/blocks/fixtures/core__pullquote.html
new file mode 100644
index 0000000000..87bd8b74f9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote.html
@@ -0,0 +1,7 @@
+<!-- wp:core/pullquote -->
+<figure class="wp-block-pullquote">
+    <blockquote>
+    <p>Testing pullquote block...</p><cite>...with a caption</cite>
+    </blockquote>
+</figure>
+<!-- /wp:core/pullquote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote.json b/tests/phpunit/data/blocks/fixtures/core__pullquote.json
new file mode 100644
index 0000000000..5cf126489b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/pullquote",
+        "isValid": true,
+        "attributes": {
+            "value": "<p>Testing pullquote block...</p>",
+            "citation": "...with a caption"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-pullquote\">\n    <blockquote>\n    <p>Testing pullquote block...</p><cite>...with a caption</cite>\n    </blockquote>\n</figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote.parsed.json b/tests/phpunit/data/blocks/fixtures/core__pullquote.parsed.json
new file mode 100644
index 0000000000..0e39eea4ec
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/pullquote",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-pullquote\">\n    <blockquote>\n    <p>Testing pullquote block...</p><cite>...with a caption</cite>\n    </blockquote>\n</figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote.serialized.html b/tests/phpunit/data/blocks/fixtures/core__pullquote.serialized.html
new file mode 100644
index 0000000000..6ef3209575
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:pullquote -->
+<figure class="wp-block-pullquote"><blockquote><p>Testing pullquote block...</p><cite>...with a caption</cite></blockquote></figure>
+<!-- /wp:pullquote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.html b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.html
new file mode 100644
index 0000000000..eace115333
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.html
@@ -0,0 +1,9 @@
+<!-- wp:core/pullquote -->
+<figure class="wp-block-pullquote">
+    <blockquote>
+        <p>Paragraph <strong>one</strong></p>
+        <p>Paragraph two</p>
+        <cite>by whomever</cite>
+	</blockquote>
+</figure>
+<!-- /wp:core/pullquote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.json b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.json
new file mode 100644
index 0000000000..81c058e5ab
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/pullquote",
+        "isValid": true,
+        "attributes": {
+            "value": "<p>Paragraph <strong>one</strong></p><p>Paragraph two</p>",
+            "citation": "by whomever"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-pullquote\">\n    <blockquote>\n        <p>Paragraph <strong>one</strong></p>\n        <p>Paragraph two</p>\n        <cite>by whomever</cite>\n\t</blockquote>\n</figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.parsed.json b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.parsed.json
new file mode 100644
index 0000000000..3b303a0d8d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/pullquote",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-pullquote\">\n    <blockquote>\n        <p>Paragraph <strong>one</strong></p>\n        <p>Paragraph two</p>\n        <cite>by whomever</cite>\n\t</blockquote>\n</figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.serialized.html b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.serialized.html
new file mode 100644
index 0000000000..333b051f19
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__pullquote__multi-paragraph.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:pullquote -->
+<figure class="wp-block-pullquote"><blockquote><p>Paragraph <strong>one</strong></p><p>Paragraph two</p><cite>by whomever</cite></blockquote></figure>
+<!-- /wp:pullquote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-1.html b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.html
new file mode 100644
index 0000000000..4bfd0ef80e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.html
@@ -0,0 +1,3 @@
+<!-- wp:core/quote -->
+<blockquote class="wp-block-quote"><p>The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.</p><cite>Matt Mullenweg, 2017</cite></blockquote>
+<!-- /wp:core/quote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-1.json b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.json
new file mode 100644
index 0000000000..cd8d15bcc9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/quote",
+        "isValid": true,
+        "attributes": {
+            "value": "<p>The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.</p>",
+            "citation": "Matt Mullenweg, 2017"
+        },
+        "innerBlocks": [],
+        "originalContent": "<blockquote class=\"wp-block-quote\"><p>The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.</p><cite>Matt Mullenweg, 2017</cite></blockquote>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-1.parsed.json b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.parsed.json
new file mode 100644
index 0000000000..12f480ef31
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/quote",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<blockquote class=\"wp-block-quote\"><p>The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.</p><cite>Matt Mullenweg, 2017</cite></blockquote>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-1.serialized.html b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.serialized.html
new file mode 100644
index 0000000000..4268c41398
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-1.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:quote -->
+<blockquote class="wp-block-quote"><p>The editor will endeavour to create a new page and post building experience that makes writing rich posts effortless, and has “blocks” to make it easy what today might take shortcodes, custom HTML, or “mystery meat” embed discovery.</p><cite>Matt Mullenweg, 2017</cite></blockquote>
+<!-- /wp:quote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-2.html b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.html
new file mode 100644
index 0000000000..d4ecdca350
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.html
@@ -0,0 +1,3 @@
+<!-- wp:core/quote {"className":"is-style-large"} -->
+<blockquote class="wp-block-quote is-style-large"><p>There is no greater agony than bearing an untold story inside you.</p><cite>Maya Angelou</cite></blockquote>
+<!-- /wp:core/quote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-2.json b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.json
new file mode 100644
index 0000000000..300770c72c
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.json
@@ -0,0 +1,14 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/quote",
+        "isValid": true,
+        "attributes": {
+            "value": "<p>There is no greater agony than bearing an untold story inside you.</p>",
+            "citation": "Maya Angelou",
+            "className": "is-style-large"
+        },
+        "innerBlocks": [],
+        "originalContent": "<blockquote class=\"wp-block-quote is-style-large\"><p>There is no greater agony than bearing an untold story inside you.</p><cite>Maya Angelou</cite></blockquote>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-2.parsed.json b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.parsed.json
new file mode 100644
index 0000000000..87a9377e2e
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/quote",
+        "attrs": {
+            "className": "is-style-large"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<blockquote class=\"wp-block-quote is-style-large\"><p>There is no greater agony than bearing an untold story inside you.</p><cite>Maya Angelou</cite></blockquote>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__quote__style-2.serialized.html b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.serialized.html
new file mode 100644
index 0000000000..b257de2408
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__quote__style-2.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:quote {"className":"is-style-large"} -->
+<blockquote class="wp-block-quote is-style-large"><p>There is no greater agony than bearing an untold story inside you.</p><cite>Maya Angelou</cite></blockquote>
+<!-- /wp:quote -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__separator.html b/tests/phpunit/data/blocks/fixtures/core__separator.html
new file mode 100644
index 0000000000..d835a48314
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__separator.html
@@ -0,0 +1,3 @@
+<!-- wp:core/separator -->
+<hr class="wp-block-separator" />
+<!-- /wp:core/separator -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__separator.json b/tests/phpunit/data/blocks/fixtures/core__separator.json
new file mode 100644
index 0000000000..12a687c00a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__separator.json
@@ -0,0 +1,10 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/separator",
+        "isValid": true,
+        "attributes": {},
+        "innerBlocks": [],
+        "originalContent": "<hr class=\"wp-block-separator\" />"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__separator.parsed.json b/tests/phpunit/data/blocks/fixtures/core__separator.parsed.json
new file mode 100644
index 0000000000..d01eb1eed1
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__separator.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/separator",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<hr class=\"wp-block-separator\" />\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__separator.serialized.html b/tests/phpunit/data/blocks/fixtures/core__separator.serialized.html
new file mode 100644
index 0000000000..cb5aeea740
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__separator.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:separator -->
+<hr class="wp-block-separator"/>
+<!-- /wp:separator -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__shortcode.html b/tests/phpunit/data/blocks/fixtures/core__shortcode.html
new file mode 100644
index 0000000000..ed4bd8928d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__shortcode.html
@@ -0,0 +1,3 @@
+<!-- wp:core/shortcode -->
+[gallery ids="238,338"]
+<!-- /wp:core/shortcode -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__shortcode.json b/tests/phpunit/data/blocks/fixtures/core__shortcode.json
new file mode 100644
index 0000000000..0f1d3e559d
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__shortcode.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/shortcode",
+        "isValid": true,
+        "attributes": {
+            "text": "[gallery ids=\"238,338\"]"
+        },
+        "innerBlocks": [],
+        "originalContent": "[gallery ids=\"238,338\"]"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__shortcode.parsed.json b/tests/phpunit/data/blocks/fixtures/core__shortcode.parsed.json
new file mode 100644
index 0000000000..70d24dc276
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__shortcode.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/shortcode",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n[gallery ids=\"238,338\"]\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__shortcode.serialized.html b/tests/phpunit/data/blocks/fixtures/core__shortcode.serialized.html
new file mode 100644
index 0000000000..293b698359
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__shortcode.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:shortcode -->
+[gallery ids="238,338"]
+<!-- /wp:shortcode -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__spacer.html b/tests/phpunit/data/blocks/fixtures/core__spacer.html
new file mode 100644
index 0000000000..e7c1e25619
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__spacer.html
@@ -0,0 +1,3 @@
+<!-- wp:spacer -->
+<div style="height:100px" aria-hidden="true" class="wp-block-spacer"></div>
+<!-- /wp:spacer -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__spacer.json b/tests/phpunit/data/blocks/fixtures/core__spacer.json
new file mode 100644
index 0000000000..a157520b75
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__spacer.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/spacer",
+        "isValid": true,
+        "attributes": {
+            "height": 100
+        },
+        "innerBlocks": [],
+        "originalContent": "<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"></div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__spacer.parsed.json b/tests/phpunit/data/blocks/fixtures/core__spacer.parsed.json
new file mode 100644
index 0000000000..8b8baa2a7f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__spacer.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/spacer",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"></div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__spacer.serialized.html b/tests/phpunit/data/blocks/fixtures/core__spacer.serialized.html
new file mode 100644
index 0000000000..e7c1e25619
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__spacer.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:spacer -->
+<div style="height:100px" aria-hidden="true" class="wp-block-spacer"></div>
+<!-- /wp:spacer -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__subhead.html b/tests/phpunit/data/blocks/fixtures/core__subhead.html
new file mode 100644
index 0000000000..61cf931896
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__subhead.html
@@ -0,0 +1,3 @@
+<!-- wp:core/subhead -->
+<p class="wp-block-subhead">This is a <em>subhead</em>.</p>
+<!-- /wp:core/subhead -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__subhead.json b/tests/phpunit/data/blocks/fixtures/core__subhead.json
new file mode 100644
index 0000000000..a0c58740e2
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__subhead.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/subhead",
+        "isValid": true,
+        "attributes": {
+            "content": "This is a <em>subhead</em>."
+        },
+        "innerBlocks": [],
+        "originalContent": "<p class=\"wp-block-subhead\">This is a <em>subhead</em>.</p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__subhead.parsed.json b/tests/phpunit/data/blocks/fixtures/core__subhead.parsed.json
new file mode 100644
index 0000000000..06ca46da1b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__subhead.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/subhead",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<p class=\"wp-block-subhead\">This is a <em>subhead</em>.</p>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__subhead.serialized.html b/tests/phpunit/data/blocks/fixtures/core__subhead.serialized.html
new file mode 100644
index 0000000000..2346819208
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__subhead.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:subhead -->
+<p class="wp-block-subhead">This is a <em>subhead</em>.</p>
+<!-- /wp:subhead -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__table.html b/tests/phpunit/data/blocks/fixtures/core__table.html
new file mode 100644
index 0000000000..b9b41659e8
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__table.html
@@ -0,0 +1,3 @@
+<!-- wp:core/table -->
+<table class="wp-block-table"><thead><tr><th>Version</th><th>Musician</th><th>Date</th></tr></thead><tbody><tr><td><a href="https://wordpress.org/news/2003/05/wordpress-now-available/">.70</a></td><td>No musician chosen.</td><td>May 27, 2003</td></tr><tr><td><a href="https://wordpress.org/news/2004/01/wordpress-10/">1.0</a></td><td>Miles Davis</td><td>January 3, 2004</td></tr><tr><td>Lots of versions skipped, see <a href="https://codex.wordpress.org/WordPress_Versions">the full list</a></td><td>&hellip;</td><td>&hellip;</td></tr><tr><td><a href="https://wordpress.org/news/2015/12/clifford/">4.4</a></td><td>Clifford Brown</td><td>December 8, 2015</td></tr><tr><td><a href="https://wordpress.org/news/2016/04/coleman/">4.5</a></td><td>Coleman Hawkins</td><td>April 12, 2016</td></tr><tr><td><a href="https://wordpress.org/news/2016/08/pepper/">4.6</a></td><td>Pepper Adams</td><td>August 16, 2016</td></tr><tr><td><a href="https://wordpress.org/news/2016/12/vaughan/">4.7</a></td><td>Sarah Vaughan</td><td>December 6, 2016</td></tr></tbody></table>
+<!-- /wp:core/table -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__table.json b/tests/phpunit/data/blocks/fixtures/core__table.json
new file mode 100644
index 0000000000..7d71d09c53
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__table.json
@@ -0,0 +1,145 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/table",
+        "isValid": true,
+        "attributes": {
+            "hasFixedLayout": false,
+            "head": [
+                {
+                    "cells": [
+                        {
+                            "content": "Version",
+                            "tag": "th"
+                        },
+                        {
+                            "content": "Musician",
+                            "tag": "th"
+                        },
+                        {
+                            "content": "Date",
+                            "tag": "th"
+                        }
+                    ]
+                }
+            ],
+            "body": [
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2003/05/wordpress-now-available/\">.70</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "No musician chosen.",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "May 27, 2003",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2004/01/wordpress-10/\">1.0</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "Miles Davis",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "January 3, 2004",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "Lots of versions skipped, see <a href=\"https://codex.wordpress.org/WordPress_Versions\">the full list</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "…",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "…",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2015/12/clifford/\">4.4</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "Clifford Brown",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "December 8, 2015",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2016/04/coleman/\">4.5</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "Coleman Hawkins",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "April 12, 2016",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2016/08/pepper/\">4.6</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "Pepper Adams",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "August 16, 2016",
+                            "tag": "td"
+                        }
+                    ]
+                },
+                {
+                    "cells": [
+                        {
+                            "content": "<a href=\"https://wordpress.org/news/2016/12/vaughan/\">4.7</a>",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "Sarah Vaughan",
+                            "tag": "td"
+                        },
+                        {
+                            "content": "December 6, 2016",
+                            "tag": "td"
+                        }
+                    ]
+                }
+            ],
+            "foot": []
+        },
+        "innerBlocks": [],
+        "originalContent": "<table class=\"wp-block-table\"><thead><tr><th>Version</th><th>Musician</th><th>Date</th></tr></thead><tbody><tr><td><a href=\"https://wordpress.org/news/2003/05/wordpress-now-available/\">.70</a></td><td>No musician chosen.</td><td>May 27, 2003</td></tr><tr><td><a href=\"https://wordpress.org/news/2004/01/wordpress-10/\">1.0</a></td><td>Miles Davis</td><td>January 3, 2004</td></tr><tr><td>Lots of versions skipped, see <a href=\"https://codex.wordpress.org/WordPress_Versions\">the full list</a></td><td>&hellip;</td><td>&hellip;</td></tr><tr><td><a href=\"https://wordpress.org/news/2015/12/clifford/\">4.4</a></td><td>Clifford Brown</td><td>December 8, 2015</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/04/coleman/\">4.5</a></td><td>Coleman Hawkins</td><td>April 12, 2016</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/08/pepper/\">4.6</a></td><td>Pepper Adams</td><td>August 16, 2016</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/12/vaughan/\">4.7</a></td><td>Sarah Vaughan</td><td>December 6, 2016</td></tr></tbody></table>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__table.parsed.json b/tests/phpunit/data/blocks/fixtures/core__table.parsed.json
new file mode 100644
index 0000000000..8c24b96113
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__table.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/table",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<table class=\"wp-block-table\"><thead><tr><th>Version</th><th>Musician</th><th>Date</th></tr></thead><tbody><tr><td><a href=\"https://wordpress.org/news/2003/05/wordpress-now-available/\">.70</a></td><td>No musician chosen.</td><td>May 27, 2003</td></tr><tr><td><a href=\"https://wordpress.org/news/2004/01/wordpress-10/\">1.0</a></td><td>Miles Davis</td><td>January 3, 2004</td></tr><tr><td>Lots of versions skipped, see <a href=\"https://codex.wordpress.org/WordPress_Versions\">the full list</a></td><td>&hellip;</td><td>&hellip;</td></tr><tr><td><a href=\"https://wordpress.org/news/2015/12/clifford/\">4.4</a></td><td>Clifford Brown</td><td>December 8, 2015</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/04/coleman/\">4.5</a></td><td>Coleman Hawkins</td><td>April 12, 2016</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/08/pepper/\">4.6</a></td><td>Pepper Adams</td><td>August 16, 2016</td></tr><tr><td><a href=\"https://wordpress.org/news/2016/12/vaughan/\">4.7</a></td><td>Sarah Vaughan</td><td>December 6, 2016</td></tr></tbody></table>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__table.serialized.html b/tests/phpunit/data/blocks/fixtures/core__table.serialized.html
new file mode 100644
index 0000000000..a791eb149f
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__table.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:table -->
+<table class="wp-block-table"><thead><tr><th>Version</th><th>Musician</th><th>Date</th></tr></thead><tbody><tr><td><a href="https://wordpress.org/news/2003/05/wordpress-now-available/">.70</a></td><td>No musician chosen.</td><td>May 27, 2003</td></tr><tr><td><a href="https://wordpress.org/news/2004/01/wordpress-10/">1.0</a></td><td>Miles Davis</td><td>January 3, 2004</td></tr><tr><td>Lots of versions skipped, see <a href="https://codex.wordpress.org/WordPress_Versions">the full list</a></td><td>…</td><td>…</td></tr><tr><td><a href="https://wordpress.org/news/2015/12/clifford/">4.4</a></td><td>Clifford Brown</td><td>December 8, 2015</td></tr><tr><td><a href="https://wordpress.org/news/2016/04/coleman/">4.5</a></td><td>Coleman Hawkins</td><td>April 12, 2016</td></tr><tr><td><a href="https://wordpress.org/news/2016/08/pepper/">4.6</a></td><td>Pepper Adams</td><td>August 16, 2016</td></tr><tr><td><a href="https://wordpress.org/news/2016/12/vaughan/">4.7</a></td><td>Sarah Vaughan</td><td>December 6, 2016</td></tr></tbody></table>
+<!-- /wp:table -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__text-columns.html b/tests/phpunit/data/blocks/fixtures/core__text-columns.html
new file mode 100644
index 0000000000..a273839c39
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text-columns.html
@@ -0,0 +1,10 @@
+<!-- wp:core/text-columns {"width":"center"} -->
+<div class="wp-block-text-columns aligncenter columns-2">
+    <div class="wp-block-column">
+        <p>One</p>
+    </div>
+    <div class="wp-block-column">
+        <p>Two</p>
+    </div>
+</div>
+<!-- /wp:core/text-columns -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__text-columns.json b/tests/phpunit/data/blocks/fixtures/core__text-columns.json
new file mode 100644
index 0000000000..f610db9e55
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text-columns.json
@@ -0,0 +1,21 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/text-columns",
+        "isValid": true,
+        "attributes": {
+            "content": [
+                {
+                    "children": "One"
+                },
+                {
+                    "children": "Two"
+                }
+            ],
+            "columns": 2,
+            "width": "center"
+        },
+        "innerBlocks": [],
+        "originalContent": "<div class=\"wp-block-text-columns aligncenter columns-2\">\n    <div class=\"wp-block-column\">\n        <p>One</p>\n    </div>\n    <div class=\"wp-block-column\">\n        <p>Two</p>\n    </div>\n</div>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__text-columns.parsed.json b/tests/phpunit/data/blocks/fixtures/core__text-columns.parsed.json
new file mode 100644
index 0000000000..293c930ac5
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text-columns.parsed.json
@@ -0,0 +1,16 @@
+[
+    {
+        "blockName": "core/text-columns",
+        "attrs": {
+            "width": "center"
+        },
+        "innerBlocks": [],
+        "innerHTML": "\n<div class=\"wp-block-text-columns aligncenter columns-2\">\n    <div class=\"wp-block-column\">\n        <p>One</p>\n    </div>\n    <div class=\"wp-block-column\">\n        <p>Two</p>\n    </div>\n</div>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__text-columns.serialized.html b/tests/phpunit/data/blocks/fixtures/core__text-columns.serialized.html
new file mode 100644
index 0000000000..8ae01efcb9
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text-columns.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:text-columns {"width":"center"} -->
+<div class="wp-block-text-columns aligncenter columns-2"><div class="wp-block-column"><p>One</p></div><div class="wp-block-column"><p>Two</p></div></div>
+<!-- /wp:text-columns -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.html b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.html
new file mode 100644
index 0000000000..a1d47a56e0
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.html
@@ -0,0 +1,3 @@
+<!-- wp:core/text -->
+<p>This is an old-style text block.  Changed to <code>paragraph</code> in #2135.</p>
+<!-- /wp:core/text -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.json b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.json
new file mode 100644
index 0000000000..2f85e75d9a
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.json
@@ -0,0 +1,13 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/paragraph",
+        "isValid": true,
+        "attributes": {
+            "content": "This is an old-style text block.  Changed to <code>paragraph</code> in #2135.",
+            "dropCap": false
+        },
+        "innerBlocks": [],
+        "originalContent": "<p>This is an old-style text block.  Changed to <code>paragraph</code> in #2135.</p>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.parsed.json b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.parsed.json
new file mode 100644
index 0000000000..958d2a2921
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/text",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<p>This is an old-style text block.  Changed to <code>paragraph</code> in #2135.</p>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.serialized.html b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.serialized.html
new file mode 100644
index 0000000000..61fd699dac
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__text__converts-to-paragraph.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>This is an old-style text block.  Changed to <code>paragraph</code> in #2135.</p>
+<!-- /wp:paragraph -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__verse.html b/tests/phpunit/data/blocks/fixtures/core__verse.html
new file mode 100644
index 0000000000..0e6904a898
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__verse.html
@@ -0,0 +1,3 @@
+<!-- wp:core/verse -->
+<pre class="wp-block-verse">A <em>verse</em>…<br>And more!</pre>
+<!-- /wp:core/verse -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__verse.json b/tests/phpunit/data/blocks/fixtures/core__verse.json
new file mode 100644
index 0000000000..5c6e3d83e6
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__verse.json
@@ -0,0 +1,12 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/verse",
+        "isValid": true,
+        "attributes": {
+            "content": "A <em>verse</em>…<br>And more!"
+        },
+        "innerBlocks": [],
+        "originalContent": "<pre class=\"wp-block-verse\">A <em>verse</em>…<br>And more!</pre>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__verse.parsed.json b/tests/phpunit/data/blocks/fixtures/core__verse.parsed.json
new file mode 100644
index 0000000000..4f244cb551
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__verse.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/verse",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<pre class=\"wp-block-verse\">A <em>verse</em>…<br>And more!</pre>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__verse.serialized.html b/tests/phpunit/data/blocks/fixtures/core__verse.serialized.html
new file mode 100644
index 0000000000..a601b25991
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__verse.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:verse -->
+<pre class="wp-block-verse">A <em>verse</em>…<br>And more!</pre>
+<!-- /wp:verse -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__video.html b/tests/phpunit/data/blocks/fixtures/core__video.html
new file mode 100644
index 0000000000..dd720ecda8
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__video.html
@@ -0,0 +1,3 @@
+<!-- wp:core/video -->
+<figure class="wp-block-video"><video controls src="https://awesome-fake.video/file.mp4"></video></figure>
+<!-- /wp:core/video -->
diff --git a/tests/phpunit/data/blocks/fixtures/core__video.json b/tests/phpunit/data/blocks/fixtures/core__video.json
new file mode 100644
index 0000000000..e91fd20c5b
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__video.json
@@ -0,0 +1,18 @@
+[
+    {
+        "clientId": "_clientId_0",
+        "name": "core/video",
+        "isValid": true,
+        "attributes": {
+            "autoplay": false,
+            "caption": "",
+            "controls": true,
+            "loop": false,
+            "muted": false,
+            "preload": "metadata",
+            "src": "https://awesome-fake.video/file.mp4"
+        },
+        "innerBlocks": [],
+        "originalContent": "<figure class=\"wp-block-video\"><video controls src=\"https://awesome-fake.video/file.mp4\"></video></figure>"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__video.parsed.json b/tests/phpunit/data/blocks/fixtures/core__video.parsed.json
new file mode 100644
index 0000000000..7b448d6f38
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__video.parsed.json
@@ -0,0 +1,14 @@
+[
+    {
+        "blockName": "core/video",
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n<figure class=\"wp-block-video\"><video controls src=\"https://awesome-fake.video/file.mp4\"></video></figure>\n"
+    },
+    {
+        "blockName": null,
+        "attrs": {},
+        "innerBlocks": [],
+        "innerHTML": "\n"
+    }
+]
diff --git a/tests/phpunit/data/blocks/fixtures/core__video.serialized.html b/tests/phpunit/data/blocks/fixtures/core__video.serialized.html
new file mode 100644
index 0000000000..48dca62aec
--- /dev/null
+++ b/tests/phpunit/data/blocks/fixtures/core__video.serialized.html
@@ -0,0 +1,3 @@
+<!-- wp:video -->
+<figure class="wp-block-video"><video controls src="https://awesome-fake.video/file.mp4"></video></figure>
+<!-- /wp:video -->
diff --git a/tests/phpunit/tests/blocks/block-parser.php b/tests/phpunit/tests/blocks/block-parser.php
new file mode 100644
index 0000000000..3818cd9816
--- /dev/null
+++ b/tests/phpunit/tests/blocks/block-parser.php
@@ -0,0 +1,120 @@
+<?php
+/**
+ * WP_Block_Parser tests.
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ * @since 5.0.0
+ */
+
+/**
+ * Tests for WP_Block_Parser
+ *
+ * @since 5.0.0
+ *
+ * @group blocks
+ */
+class WP_Test_Block_Parser extends WP_UnitTestCase {
+	/**
+	 * The location of the fixtures to test with.
+	 *
+	 * @since 5.0.0
+	 * @var string
+	 */
+	protected static $fixtures_dir;
+
+	/**
+	 * @ticket 45109
+	 */
+	public function data_parsing_test_filenames() {
+		self::$fixtures_dir = DIR_TESTDATA . '/blocks/fixtures';
+
+		$fixture_filenames = array_merge(
+			glob( self::$fixtures_dir . '/*.json' ),
+			glob( self::$fixtures_dir . '/*.html' )
+		);
+
+		$fixture_filenames = array_values(
+			array_unique(
+				array_map(
+					array( $this, 'clean_fixture_filename' ),
+					$fixture_filenames
+				)
+			)
+		);
+
+		return array_map(
+			array( $this, 'pass_parser_fixture_filenames' ),
+			$fixture_filenames
+		);
+	}
+
+	/**
+	 * @dataProvider data_parsing_test_filenames
+	 * @ticket 45109
+	 */
+	public function test_default_parser_output( $html_filename, $parsed_json_filename ) {
+		$html_path        = self::$fixtures_dir . '/' . $html_filename;
+		$parsed_json_path = self::$fixtures_dir . '/' . $parsed_json_filename;
+
+		foreach ( array( $html_path, $parsed_json_path ) as $filename ) {
+			if ( ! file_exists( $filename ) ) {
+				//throw new Exception( "Missing fixture file: '$filename'" );
+			}
+		}
+
+		$html            = self::strip_r( file_get_contents( $html_path ) );
+		$expected_parsed = json_decode( self::strip_r( file_get_contents( $parsed_json_path ) ), true );
+
+		$parser = new WP_Block_Parser();
+		$result = json_decode( json_encode( $parser->parse( $html ) ), true );
+
+		$this->assertEquals(
+			$expected_parsed,
+			$result,
+			"File '$parsed_json_filename' does not match expected value"
+		);
+	}
+
+	/**
+	 * Helper function to remove relative paths and extension from a filename, leaving just the fixture name.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param string $filename The filename to clean.
+	 * @return string The cleaned fixture name.
+	 */
+	protected function clean_fixture_filename( $filename ) {
+		$filename = basename( $filename );
+		$filename = preg_replace( '/\..+$/', '', $filename );
+		return $filename;
+	}
+
+	/**
+	 * Helper function to return the filenames needed to test the parser output.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param string $filename The cleaned fixture name.
+	 * @return array The input and expected output filenames for that fixture.
+	 */
+	protected function pass_parser_fixture_filenames( $filename ) {
+		return array(
+			"$filename.html",
+			"$filename.parsed.json",
+		);
+	}
+
+	/**
+	 * Helper function to remove '\r' characters from a string.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param string $input The string to remove '\r' from.
+	 * @return string The input string, with '\r' characters removed.
+	 */
+	protected function strip_r( $input ) {
+		return str_replace( "\r", '', $input );
+	}
+
+}
diff --git a/tools/webpack/packages.js b/tools/webpack/packages.js
index 3040d854d7..9376d37e1b 100644
--- a/tools/webpack/packages.js
+++ b/tools/webpack/packages.js
@@ -116,6 +116,10 @@ module.exports = function( env = { environment: 'production', watch: false } ) {
 		'wp-polyfill-node-contains.min.js': 'polyfill-library/polyfills/Node/prototype/contains/polyfill.js',
 	};
 
+	const phpFiles = {
+		'block-serialization-default-parser/parser.php': 'wp-includes/class-wp-block-parser.php',
+	};
+
 	const externals = {
 		react: 'React',
 		'react-dom': 'ReactDOM',
@@ -164,6 +168,11 @@ module.exports = function( env = { environment: 'production', watch: false } ) {
 		}
 	} ) );
 
+	const phpCopies = Object.keys( phpFiles ).map( ( filename ) => ( {
+		from: join( baseDir, `node_modules/@wordpress/${ filename }` ),
+		to: join( baseDir, `src/${ phpFiles[ filename ] }` ),
+	} ) );
+
 	const config = {
 		mode,
 
@@ -232,6 +241,7 @@ module.exports = function( env = { environment: 'production', watch: false } ) {
 				[
 					...vendorCopies,
 					...cssCopies,
+					...phpCopies,
 				],
 			),
 		],