Writing flow: fix Cmd+A from empty RichText (WordPress#75175)

Co-authored-by: ellatrix <ellatrix@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

Author: ellatrix

packages/dom/src/dom/is-entirely-selected.js

@@ -4,6 +4,12 @@
 import { assertIsDefined } from '../utils/assert-is-defined';
 import isInputOrTextArea from './is-input-or-text-area';
 
+/**
+ * Zero width non-breaking space, used as padding in the editable DOM tree when
+ * it is empty otherwise.
+ */
+const ZWNBSP = '\ufeff';
+
 /**
  * Check whether the contents of the element have been entirely selected.
  * Returns true if there is no possibility of selection.
@@ -24,6 +30,14 @@ export default function isEntirelySelected( element ) {
 		return true;
 	}
 
+	// If the element is effectively empty (contains only the ZWNBSP
+	// placeholder or nothing), consider it entirely selected since there's
+	// nothing meaningful to select.
+	const text = element.textContent || '';
+	if ( text === '' || text === ZWNBSP ) {
+		return true;
+	}
+
 	const { ownerDocument } = element;
 	const { defaultView } = ownerDocument;
 	assertIsDefined( defaultView, 'defaultView' );

test/e2e/specs/editor/blocks/list.spec.js

@@ -1655,4 +1655,40 @@ test.describe( 'List (@firefox)', () => {
 			},
 		] );
 	} );
+
+	test( 'should select the list wrapper with select all in empty list item', async ( {
+		editor,
+		page,
+		pageUtils,
+	} ) => {
+		await editor.insertBlock( { name: 'core/list' } );
+
+		// Verify the list item is selected after insertion.
+		await expect
+			.poll( () =>
+				page.evaluate(
+					() =>
+						window.wp.data
+							.select( 'core/block-editor' )
+							.getSelectedBlock()?.name
+				)
+			)
+			.toBe( 'core/list-item' );
+
+		// The list item is empty. Press cmd+a to select all, then again to select the list block.
+		await pageUtils.pressKeys( 'primary+a' );
+		await pageUtils.pressKeys( 'primary+a' );
+
+		// Verify the list block is selected using the block-editor store.
+		await expect
+			.poll( () =>
+				page.evaluate(
+					() =>
+						window.wp.data
+							.select( 'core/block-editor' )
+							.getSelectedBlock()?.name
+				)
+			)
+			.toBe( 'core/list' );
+	} );
 } );