diff --git a/tests/phpunit/tests/dependencies/scripts.php b/tests/phpunit/tests/dependencies/scripts.php
index efe5a7ba6f..c7d3f813ef 100644
--- a/tests/phpunit/tests/dependencies/scripts.php
+++ b/tests/phpunit/tests/dependencies/scripts.php
@@ -724,4 +724,360 @@ class Tests_Dependencies_Scripts extends WP_UnitTestCase {
 
 		$this->assertEquals( $expected, get_echo( 'wp_print_scripts' ) );
 	}
+
+	/**
+	 * Testing `wp_enqueue_code_editor` with file path.
+	 *
+	 * @ticket 41871
+	 * @covers wp_enqueue_code_editor()
+	 */
+	public function test_wp_enqueue_code_editor_when_php_file_will_be_passed() {
+		$real_file = WP_PLUGIN_DIR . '/hello.php';
+		$wp_enqueue_code_editor = wp_enqueue_code_editor( array( 'file' => $real_file ) );
+		$this->assertNonEmptyMultidimensionalArray( $wp_enqueue_code_editor );
+
+		$this->assertEqualSets( array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ), array_keys( $wp_enqueue_code_editor ) );
+		$this->assertEqualSets(
+			array(
+				'autoCloseBrackets',
+				'autoCloseTags',
+				'continueComments',
+				'direction',
+				'extraKeys',
+				'indentUnit',
+				'indentWithTabs',
+				'inputStyle',
+				'lineNumbers',
+				'lineWrapping',
+				'matchBrackets',
+				'matchTags',
+				'mode',
+				'styleActiveLine',
+			),
+			array_keys( $wp_enqueue_code_editor['codemirror'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'errors',
+				'box-model',
+				'display-property-grouping',
+				'duplicate-properties',
+				'known-properties',
+				'outline-none',
+			),
+			array_keys( $wp_enqueue_code_editor['csslint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'boss',
+				'curly',
+				'eqeqeq',
+				'eqnull',
+				'es3',
+				'expr',
+				'immed',
+				'noarg',
+				'nonbsp',
+				'onevar',
+				'quotmark',
+				'trailing',
+				'undef',
+				'unused',
+				'browser',
+				'globals',
+			),
+			array_keys( $wp_enqueue_code_editor['jshint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'tagname-lowercase',
+				'attr-lowercase',
+				'attr-value-double-quotes',
+				'doctype-first',
+				'tag-pair',
+				'spec-char-escape',
+				'id-unique',
+				'src-not-empty',
+				'attr-no-duplication',
+				'alt-require',
+				'space-tab-mixed-disabled',
+				'attr-unsafe-chars',
+			),
+			array_keys( $wp_enqueue_code_editor['htmlhint'] )
+		);
+	}
+
+	/**
+	 * Testing `wp_enqueue_code_editor` with `compact`.
+	 *
+	 * @ticket 41871
+	 * @covers wp_enqueue_code_editor()
+	 */
+	public function test_wp_enqueue_code_editor_when_generated_array_by_compact_will_be_passed() {
+		$wp_enqueue_code_editor = wp_enqueue_code_editor( compact( 'file' ) );
+		$this->assertNonEmptyMultidimensionalArray( $wp_enqueue_code_editor );
+
+		$this->assertEqualSets( array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ), array_keys( $wp_enqueue_code_editor ) );
+		$this->assertEqualSets(
+			array(
+				'continueComments',
+				'direction',
+				'extraKeys',
+				'indentUnit',
+				'indentWithTabs',
+				'inputStyle',
+				'lineNumbers',
+				'lineWrapping',
+				'mode',
+				'styleActiveLine',
+			),
+			array_keys( $wp_enqueue_code_editor['codemirror'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'errors',
+				'box-model',
+				'display-property-grouping',
+				'duplicate-properties',
+				'known-properties',
+				'outline-none',
+			),
+			array_keys( $wp_enqueue_code_editor['csslint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'boss',
+				'curly',
+				'eqeqeq',
+				'eqnull',
+				'es3',
+				'expr',
+				'immed',
+				'noarg',
+				'nonbsp',
+				'onevar',
+				'quotmark',
+				'trailing',
+				'undef',
+				'unused',
+				'browser',
+				'globals',
+			),
+			array_keys( $wp_enqueue_code_editor['jshint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'tagname-lowercase',
+				'attr-lowercase',
+				'attr-value-double-quotes',
+				'doctype-first',
+				'tag-pair',
+				'spec-char-escape',
+				'id-unique',
+				'src-not-empty',
+				'attr-no-duplication',
+				'alt-require',
+				'space-tab-mixed-disabled',
+				'attr-unsafe-chars',
+			),
+			array_keys( $wp_enqueue_code_editor['htmlhint'] )
+		);
+	}
+
+	/**
+	 * Testing `wp_enqueue_code_editor` with `array_merge`.
+	 *
+	 * @ticket 41871
+	 * @covers wp_enqueue_code_editor()
+	 */
+	public function test_wp_enqueue_code_editor_when_generated_array_by_array_merge_will_be_passed() {
+		$wp_enqueue_code_editor = wp_enqueue_code_editor(
+			array_merge(
+				array(
+					'type' => 'text/css',
+					'codemirror' => array(
+						'indentUnit' => 2,
+						'tabSize' => 2,
+					),
+				),
+				array()
+			)
+		);
+
+		$this->assertNonEmptyMultidimensionalArray( $wp_enqueue_code_editor );
+
+		$this->assertEqualSets( array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ), array_keys( $wp_enqueue_code_editor ) );
+		$this->assertEqualSets(
+			array(
+				'autoCloseBrackets',
+				'continueComments',
+				'direction',
+				'extraKeys',
+				'gutters',
+				'indentUnit',
+				'indentWithTabs',
+				'inputStyle',
+				'lineNumbers',
+				'lineWrapping',
+				'lint',
+				'matchBrackets',
+				'mode',
+				'styleActiveLine',
+				'tabSize',
+			),
+			array_keys( $wp_enqueue_code_editor['codemirror'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'errors',
+				'box-model',
+				'display-property-grouping',
+				'duplicate-properties',
+				'known-properties',
+				'outline-none',
+			),
+			array_keys( $wp_enqueue_code_editor['csslint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'boss',
+				'curly',
+				'eqeqeq',
+				'eqnull',
+				'es3',
+				'expr',
+				'immed',
+				'noarg',
+				'nonbsp',
+				'onevar',
+				'quotmark',
+				'trailing',
+				'undef',
+				'unused',
+				'browser',
+				'globals',
+			),
+			array_keys( $wp_enqueue_code_editor['jshint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'tagname-lowercase',
+				'attr-lowercase',
+				'attr-value-double-quotes',
+				'doctype-first',
+				'tag-pair',
+				'spec-char-escape',
+				'id-unique',
+				'src-not-empty',
+				'attr-no-duplication',
+				'alt-require',
+				'space-tab-mixed-disabled',
+				'attr-unsafe-chars',
+			),
+			array_keys( $wp_enqueue_code_editor['htmlhint'] )
+		);
+	}
+
+	/**
+	 * Testing `wp_enqueue_code_editor` with `array`.
+	 *
+	 * @ticket 41871
+	 * @covers wp_enqueue_code_editor()
+	 */
+	public function test_wp_enqueue_code_editor_when_simple_array_will_be_passed() {
+		$wp_enqueue_code_editor = wp_enqueue_code_editor(
+			array(
+				'type' => 'text/css',
+				'codemirror' => array(
+					'indentUnit' => 2,
+					'tabSize' => 2,
+				),
+			)
+		);
+
+		$this->assertNonEmptyMultidimensionalArray( $wp_enqueue_code_editor );
+
+		$this->assertEqualSets( array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ), array_keys( $wp_enqueue_code_editor ) );
+		$this->assertEqualSets(
+			array(
+				'autoCloseBrackets',
+				'continueComments',
+				'direction',
+				'extraKeys',
+				'gutters',
+				'indentUnit',
+				'indentWithTabs',
+				'inputStyle',
+				'lineNumbers',
+				'lineWrapping',
+				'lint',
+				'matchBrackets',
+				'mode',
+				'styleActiveLine',
+				'tabSize',
+			),
+			array_keys( $wp_enqueue_code_editor['codemirror'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'errors',
+				'box-model',
+				'display-property-grouping',
+				'duplicate-properties',
+				'known-properties',
+				'outline-none',
+			),
+			array_keys( $wp_enqueue_code_editor['csslint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'boss',
+				'curly',
+				'eqeqeq',
+				'eqnull',
+				'es3',
+				'expr',
+				'immed',
+				'noarg',
+				'nonbsp',
+				'onevar',
+				'quotmark',
+				'trailing',
+				'undef',
+				'unused',
+				'browser',
+				'globals',
+			),
+			array_keys( $wp_enqueue_code_editor['jshint'] )
+		);
+
+		$this->assertEqualSets(
+			array(
+				'tagname-lowercase',
+				'attr-lowercase',
+				'attr-value-double-quotes',
+				'doctype-first',
+				'tag-pair',
+				'spec-char-escape',
+				'id-unique',
+				'src-not-empty',
+				'attr-no-duplication',
+				'alt-require',
+				'space-tab-mixed-disabled',
+				'attr-unsafe-chars',
+			),
+			array_keys( $wp_enqueue_code_editor['htmlhint'] )
+		);
+	}
 }
diff --git a/tests/phpunit/tests/widgets/custom-html-widget.php b/tests/phpunit/tests/widgets/custom-html-widget.php
index 35dac8462a..69623fbd65 100644
--- a/tests/phpunit/tests/widgets/custom-html-widget.php
+++ b/tests/phpunit/tests/widgets/custom-html-widget.php
@@ -28,23 +28,54 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	protected $widget_text_args;
 
 	/**
-	 * Test constructor.
+	 * Clean up global scope.
 	 *
-	 * @covers WP_Widget_Custom_HTML::__constructor
+	 * @global WP_Scripts $wp_scripts
+	 * @global WP_Styles  $wp_style
 	 */
-	function test_constructor() {
+	public function clean_up_global_scope() {
+		global $wp_scripts, $wp_styles;
+		parent::clean_up_global_scope();
+		$wp_scripts = null;
+		$wp_styles = null;
+	}
+
+	/**
+	 * Test construct.
+	 *
+	 * @covers WP_Widget_Custom_HTML::__construct
+	 */
+	public function test_construct() {
 		$widget = new WP_Widget_Custom_HTML();
 		$this->assertEquals( 'custom_html', $widget->id_base );
 		$this->assertEquals( 'widget_custom_html', $widget->widget_options['classname'] );
+		$this->assertEquals( 400, $widget->control_options['width'] );
+		$this->assertEquals( 350, $widget->control_options['height'] );
 		$this->assertTrue( $widget->widget_options['customize_selective_refresh'] );
 	}
 
+	/**
+	 * Test enqueue_admin_scripts method.
+	 *
+	 * @covers WP_Widget_Custom_HTML::_register
+	 */
+	public function test__register() {
+		set_current_screen( 'widgets.php' );
+		$widget = new WP_Widget_Custom_HTML();
+		$widget->_register();
+
+		$this->assertEquals( 10, has_action( 'admin_print_scripts-widgets.php', array( $widget, 'enqueue_admin_scripts' ) ) );
+		$this->assertEquals( 10, has_action( 'admin_footer-widgets.php', array( 'WP_Widget_Custom_HTML', 'render_control_template_scripts' ) ) );
+		$this->assertEquals( 10, has_action( 'admin_head-widgets.php', array( 'WP_Widget_Custom_HTML', 'add_help_text' ) ) );
+		$this->assertContains( 'wp.customHtmlWidgets.idBases.push( "custom_html" );', wp_scripts()->registered['custom-html-widgets']->extra['after'] );
+	}
+
 	/**
 	 * Test widget method.
 	 *
 	 * @covers WP_Widget_Custom_HTML::widget
 	 */
-	function test_widget() {
+	public function test_widget() {
 		$widget = new WP_Widget_Custom_HTML();
 		$content = "<i>Custom HTML</i>\n\n<b>CODE</b>\nLast line.<u>unclosed";
 
@@ -105,7 +136,7 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	 * @param WP_Widget_Custom_HTML $widget   Current widget instance.
 	 * @return string Widget content.
 	 */
-	function filter_widget_text( $text, $instance, $widget ) {
+	public function filter_widget_text( $text, $instance, $widget ) {
 		$this->widget_text_args = array( $text, $instance, $widget );
 		$text .= '[filter:widget_text]';
 		return $text;
@@ -119,7 +150,7 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	 * @param WP_Widget_Custom_HTML $widget         Current Custom HTML widget instance.
 	 * @return string Widget content.
 	 */
-	function filter_widget_custom_html_content( $widget_content, $instance, $widget ) {
+	public function filter_widget_custom_html_content( $widget_content, $instance, $widget ) {
 		$this->widget_custom_html_content_args = array( $widget_content, $instance, $widget );
 		$widget_content .= '[filter:widget_custom_html_content]';
 		return $widget_content;
@@ -130,7 +161,7 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	 *
 	 * @covers WP_Widget_Custom_HTML::update
 	 */
-	function test_update() {
+	public function test_update() {
 		$widget = new WP_Widget_Custom_HTML();
 		$instance = array(
 			'title'   => "The\n<b>Title</b>",
@@ -174,7 +205,7 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	 * @param string $cap     Capability name.
 	 * @return array Caps.
 	 */
-	function grant_unfiltered_html_cap( $caps, $cap ) {
+	public function grant_unfiltered_html_cap( $caps, $cap ) {
 		if ( 'unfiltered_html' === $cap ) {
 			$caps = array_diff( $caps, array( 'do_not_allow' ) );
 			$caps[] = 'unfiltered_html';
@@ -189,11 +220,79 @@ class Test_WP_Widget_Custom_HTML extends WP_UnitTestCase {
 	 * @param string $cap     Capability name.
 	 * @return array Caps.
 	 */
-	function revoke_unfiltered_html_cap( $caps, $cap ) {
+	public function revoke_unfiltered_html_cap( $caps, $cap ) {
 		if ( 'unfiltered_html' === $cap ) {
 			$caps = array_diff( $caps, array( 'unfiltered_html' ) );
 			$caps[] = 'do_not_allow';
 		}
 		return $caps;
 	}
+
+	/**
+	 * Test enqueue_admin_scripts method. Condition: logged_in, syntax_highlighting is on.
+	 *
+	 * @covers WP_Widget_Custom_HTML::enqueue_admin_scripts
+	 */
+	public function test_enqueue_admin_scripts_when_logged_in_and_syntax_highlighting_on() {
+		$user = $this->factory()->user->create();
+		wp_set_current_user( $user );
+		wp_get_current_user()->syntax_highlighting = 'true';
+		set_current_screen( 'widgets.php' );
+		$widget = new WP_Widget_Custom_HTML();
+		$widget->enqueue_admin_scripts();
+
+		$this->assertTrue( wp_script_is( 'custom-html-widgets', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'code-editor', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'wp-codemirror', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'csslint', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'jshint', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'htmlhint', 'enqueued' ) );
+	}
+
+	/**
+	 * Test enqueue_admin_scripts method. Condition: logged_in, syntax_highlighting is off.
+	 *
+	 * @covers WP_Widget_Custom_HTML::enqueue_admin_scripts
+	 */
+	public function test_enqueue_admin_scripts_when_logged_in_and_syntax_highlighting_off() {
+		$user = $this->factory()->user->create();
+		wp_set_current_user( $user );
+		update_user_meta( $user, 'syntax_highlighting', 'false' );
+		set_current_screen( 'widgets.php' );
+		$widget = new WP_Widget_Custom_HTML();
+		$widget->enqueue_admin_scripts();
+
+		$this->assertTrue( wp_script_is( 'custom-html-widgets', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'code-editor', 'enqueued' ) );
+		$this->assertTrue( wp_script_is( 'wp-codemirror', 'enqueued' ) );
+		$this->assertFalse( wp_script_is( 'csslint', 'enqueued' ) );
+		$this->assertFalse( wp_script_is( 'jshint', 'enqueued' ) );
+		$this->assertFalse( wp_script_is( 'htmlhint', 'enqueued' ) );
+	}
+
+	/**
+	 * Test render_control_template_scripts method.
+	 *
+	 * @covers WP_Widget_Custom_HTML::render_control_template_scripts
+	 */
+	public function test_render_control_template_scripts() {
+		ob_start();
+		WP_Widget_Custom_HTML::render_control_template_scripts();
+		$output = ob_get_clean();
+
+		$this->assertContains( '<script type="text/html" id="tmpl-widget-custom-html-control-fields">', $output );
+	}
+
+	/**
+	 * Test add_help_text method.
+	 *
+	 * @covers WP_Widget_Custom_HTML::add_help_text
+	 */
+	public function test_add_help_text() {
+		set_current_screen( 'widgets.php' );
+		WP_Widget_Custom_HTML::add_help_text();
+		$content = get_current_screen()->get_help_tab( 'custom_html_widget' )['content'];
+
+		$this->assertContains( 'Use the Custom HTML widget to add arbitrary HTML code to your widget areas.', $content );
+	}
 }