Fix UrlInput combobox to use the ARIA 1.0 pattern. (#47148)

* Fix UrlInput combobox to use the ARIA 1.0 pattern.

* Update changelog.

* Improve testing for correct ARIA combobox pattern.

* Add and clarify test comments.

changelog.txt

@@ -449,6 +449,8 @@ The following contributors merged PRs in this release:
 #### Block Library
 - Lodash: Remove `_.pickBy()` from latest posts block. ([46974](https://github.com/WordPress/gutenberg/pull/46974))
 
+### Accessibility
+- Block Editor: Revert `aria-controls` to `aria-owns` in `URLInput` to use the more broadly supported ARIA 1.0 combobox pattern. ([47148](https://github.com/WordPress/gutenberg/pull/47148))
 
 ### Experiments
 

packages/block-editor/src/components/link-control/test/index.js

@@ -137,7 +137,122 @@ describe( 'Basic rendering', () => {
 		// Search Input UI.
 		const searchInput = screen.getByRole( 'combobox', { name: 'URL' } );
 
-		expect( searchInput ).toBeInTheDocument();
+		expect( searchInput ).toBeVisible();
+	} );
+
+	it( 'should have aria-owns attribute to follow the ARIA 1.0 pattern', () => {
+		render( <LinkControl /> );
+
+		// Search Input UI.
+		const searchInput = screen.getByRole( 'combobox', { name: 'URL' } );
+
+		expect( searchInput ).toBeVisible();
+		// Make sure we use the ARIA 1.0 pattern with aria-owns.
+		// See https://github.com/WordPress/gutenberg/issues/47147
+		expect( searchInput ).not.toHaveAttribute( 'aria-controls' );
+		expect( searchInput ).toHaveAttribute( 'aria-owns' );
+	} );
+
+	it( 'should have aria-selected attribute only on the highlighted item', async () => {
+		const user = userEvent.setup();
+
+		let resolver;
+		mockFetchSearchSuggestions.mockImplementation(
+			() =>
+				new Promise( ( resolve ) => {
+					resolver = resolve;
+				} )
+		);
+
+		render( <LinkControl /> );
+
+		// Search Input UI.
+		const searchInput = screen.getByRole( 'combobox', { name: 'URL' } );
+
+		// Simulate searching for a term.
+		await user.type( searchInput, 'Hello' );
+
+		// Wait for the spinner SVG icon to be rendered.
+		expect( await screen.findByRole( 'presentation' ) ).toBeVisible();
+		// Check the suggestions list is not rendered yet.
+		expect( screen.queryByRole( 'listbox' ) ).not.toBeInTheDocument();
+
+		// Make the search suggestions fetch return a response.
+		resolver( fauxEntitySuggestions );
+
+		const resultsList = await screen.findByRole( 'listbox', {
+			name: 'Search results for "Hello"',
+		} );
+
+		// Check the suggestions list is rendered.
+		expect( resultsList ).toBeVisible();
+		// Check the spinner SVG icon is not rendered any longer.
+		expect( screen.queryByRole( 'presentation' ) ).not.toBeInTheDocument();
+
+		const searchResultElements =
+			within( resultsList ).getAllByRole( 'option' );
+
+		expect( searchResultElements ).toHaveLength(
+			// The fauxEntitySuggestions length plus the 'Press ENTER to add this link' button.
+			fauxEntitySuggestions.length + 1
+		);
+
+		// Step down into the search results, highlighting the first result item.
+		triggerArrowDown( searchInput );
+
+		const firstSearchSuggestion = searchResultElements[ 0 ];
+		const secondSearchSuggestion = searchResultElements[ 1 ];
+
+		let selectedSearchResultElement = screen.getByRole( 'option', {
+			selected: true,
+		} );
+
+		// We should have highlighted the first item using the keyboard.
+		expect( selectedSearchResultElement ).toEqual( firstSearchSuggestion );
+
+		// Check the aria-selected attribute is set only on the highlighted item.
+		expect( firstSearchSuggestion ).toHaveAttribute(
+			'aria-selected',
+			'true'
+		);
+		// Check the aria-selected attribute is omitted on the non-highlighted items.
+		expect( secondSearchSuggestion ).not.toHaveAttribute( 'aria-selected' );
+
+		// Step down into the search results, highlighting the second result item.
+		triggerArrowDown( searchInput );
+
+		selectedSearchResultElement = screen.getByRole( 'option', {
+			selected: true,
+		} );
+
+		// We should have highlighted the first item using the keyboard.
+		expect( selectedSearchResultElement ).toEqual( secondSearchSuggestion );
+
+		// Check the aria-selected attribute is omitted on non-highlighted items.
+		expect( firstSearchSuggestion ).not.toHaveAttribute( 'aria-selected' );
+		// Check the aria-selected attribute is set only on the highlighted item.
+		expect( secondSearchSuggestion ).toHaveAttribute(
+			'aria-selected',
+			'true'
+		);
+
+		// Step up into the search results, highlighting the first result item.
+		triggerArrowUp( searchInput );
+
+		selectedSearchResultElement = screen.getByRole( 'option', {
+			selected: true,
+		} );
+
+		// We should be back to highlighting the first search result again.
+		expect( selectedSearchResultElement ).toEqual( firstSearchSuggestion );
+
+		// Check the aria-selected attribute is set only on the highlighted item.
+		expect( firstSearchSuggestion ).toHaveAttribute(
+			'aria-selected',
+			'true'
+		);
+		// Check the aria-selected attribute is omitted on non-highlighted items.
+		expect( secondSearchSuggestion ).not.toHaveAttribute( 'aria-selected' );
 	} );
 
 	it( 'should not render protocol in links', async () => {
@@ -559,7 +674,7 @@ describe( 'Manual link entry', () => {
 				} );
 
 				// Verify the UI hasn't allowed submission.
-				expect( searchInput ).toBeInTheDocument();
+				expect( searchInput ).toBeVisible();
 				expect( submitButton ).toBeDisabled();
 				expect( submitButton ).toBeVisible();
 			}
@@ -601,7 +716,7 @@ describe( 'Manual link entry', () => {
 				} );
 
 				// Verify the UI hasn't allowed submission.
-				expect( searchInput ).toBeInTheDocument();
+				expect( searchInput ).toBeVisible();
 				expect( submitButton ).toBeDisabled();
 				expect( submitButton ).toBeVisible();
 			}

packages/block-editor/src/components/url-input/index.js

@@ -468,7 +468,7 @@ class URLInput extends Component {
 			'aria-label': label ? undefined : __( 'URL' ), // Ensure input always has an accessible label
 			'aria-expanded': showSuggestions,
 			'aria-autocomplete': 'list',
-			'aria-controls': suggestionsListboxId,
+			'aria-owns': suggestionsListboxId,
 			'aria-activedescendant':
 				selectedSuggestion !== null
 					? `${ suggestionOptionIdPrefix }-${ selectedSuggestion }`
@@ -531,7 +531,8 @@ class URLInput extends Component {
 				tabIndex: '-1',
 				id: `${ suggestionOptionIdPrefix }-${ index }`,
 				ref: this.bindSuggestionNode( index ),
-				'aria-selected': index === selectedSuggestion,
+				'aria-selected':
+					index === selectedSuggestion ? true : undefined,
 			};
 		};