From 9fb4d30adab5333ba4ec32b4a2f166e014544491 Mon Sep 17 00:00:00 2001
From: Pascal Birchler <swissspidy@git.wordpress.org>
Date: Tue, 23 Feb 2016 22:49:17 +0000
Subject: [PATCH] Posts: Introduce `get_post_types_by_support()`.

Similar to `get_post_types()`, this new function returns a list of post type names that support a specific feature.

Props wpsmith, barryceelen, swissspidy.
Fixes #34010.

git-svn-id: https://develop.svn.wordpress.org/trunk@36652 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/post.php           | 22 ++++++++++++++
 tests/phpunit/tests/post/types.php | 49 ++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 70a7d73e07..efb7330b52 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -1638,6 +1638,28 @@ function post_type_supports( $post_type, $feature ) {
 	return ( isset( $_wp_post_type_features[$post_type][$feature] ) );
 }
 
+/**
+ * Get a list of post type names that support a specific feature.
+ *
+ * @since 4.5.0
+ *
+ * @global array $_wp_post_type_features
+ *
+ * @param array|string $args     Single feature or an array of features the post types should support.
+ * @param string       $operator Optional. The logical operation to perform. 'or' means
+ *                               only one element from the array needs to match; 'and'
+ *                               means all elements must match; 'not' means no elements may
+ *                               match. Default 'and'.
+ * @return array A list of post type names.
+ */
+function get_post_types_by_support( $args, $operator = 'and' ) {
+	global $_wp_post_type_features;
+
+	$features = array_fill_keys( (array) $args, true );
+
+	return array_keys( wp_filter_object_list( $_wp_post_type_features, $features, $operator ) );
+}
+
 /**
  * Update the post type for the post ID.
  *
diff --git a/tests/phpunit/tests/post/types.php b/tests/phpunit/tests/post/types.php
index 9d19a84213..9cf44c84fb 100644
--- a/tests/phpunit/tests/post/types.php
+++ b/tests/phpunit/tests/post/types.php
@@ -379,4 +379,53 @@ class Tests_Post_Types extends WP_UnitTestCase {
 
 		$this->assertFalse( post_type_exists( 'foo' ) );
 	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_single_feature() {
+		$this->assertContains( 'post', get_post_types_by_support( 'title' ) );
+		$this->assertContains( 'page', get_post_types_by_support( 'title' ) );
+		$this->assertContains( 'attachment', get_post_types_by_support( 'title' ) );
+		$this->assertContains( 'nav_menu_item', get_post_types_by_support( 'title' ) );
+	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_multiple_features() {
+		$this->assertContains( 'post', get_post_types_by_support( array( 'thumbnail', 'author' ) ) );
+		$this->assertContains( 'page', get_post_types_by_support( array( 'thumbnail', 'author' ) ) );
+	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_or_operator() {
+		$this->assertContains( 'post', get_post_types_by_support( array( 'post-formats', 'page-attributes' ), 'or' ) );
+		$this->assertContains( 'page', get_post_types_by_support( array( 'post-formats', 'page-attributes' ), 'or' ) );
+	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_not_operator() {
+		$this->assertContains( 'attachment', get_post_types_by_support( array( 'thumbnail' ), 'not' ) );
+		$this->assertContains( 'revision', get_post_types_by_support( array( 'thumbnail' ), 'not' ) );
+		$this->assertContains( 'nav_menu_item', get_post_types_by_support( array( 'thumbnail' ), 'not' ) );
+	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_excluding_features() {
+		$this->assertEqualSets( array(), get_post_types_by_support( array( 'post-formats', 'page-attributes' ) ) );
+	}
+
+	/**
+	 * @ticket 34010
+	 */
+	public function test_get_post_types_by_support_non_existant_feature() {
+		$this->assertEqualSets( array(), get_post_types_by_support( 'somefeature' ) );
+	}
 }