Add basic test coverage for Navigation Menu editing mode (#56871)

* Smoke test for key behaviours

* Update test/e2e/specs/site-editor/navigation-editor.spec.js

Co-authored-by: Ben Dwyer <ben@scruffian.com>

* Use assertion

* Prefer role selector

* Use steps to break up test

---------

Co-authored-by: Andrei Draganescu <me@andreidraganescu.info>
Co-authored-by: Ben Dwyer <ben@scruffian.com>

test/e2e/specs/site-editor/navigation-editor.spec.js

@@ -0,0 +1,155 @@
+/**
+ * WordPress dependencies
+ */
+const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
+
+test.describe( 'Editing Navigation Menus', () => {
+	test.beforeAll( async ( { requestUtils } ) => {
+		await requestUtils.activateTheme( 'emptytheme' );
+	} );
+
+	test.afterEach( async ( { requestUtils } ) => {
+		await requestUtils.deleteAllMenus();
+	} );
+
+	test( 'it should lock the root Navigation block in the editor', async ( {
+		admin,
+		page,
+		pageUtils,
+		requestUtils,
+		editor,
+	} ) => {
+		await test.step( 'Manually browse to focus mode for a Navigation Menu', async () => {
+			// We could Navigate directly to editing the Navigation Menu but we intentionally do not do this.
+			//
+			// Why? To provide coverage for a bug that caused the Navigation Editor behaviours to fail
+			// only when navigating through the editor screens (rather than going directly to the editor by URL).
+			// See: https://github.com/WordPress/gutenberg/pull/56856.
+			//
+			// Example (what we could do):
+			// await admin.visitSiteEditor( {
+			// 	postId: createdMenu?.id,
+			// 	postType: 'wp_navigation',
+			// } );
+			//
+			await admin.visitSiteEditor();
+
+			// create a Navigation Menu called "Test Menu" using the REST API helpers
+			const createdMenu = await requestUtils.createNavigationMenu( {
+				title: 'Primary Menu',
+				content:
+					'<!-- wp:navigation-link {"label":"WordPress","type":"custom","url":"http://www.wordpress.org/","kind":"custom"} /-->',
+			} );
+
+			// Add another so we get a list of Navigation menus in the editor.
+			await requestUtils.createNavigationMenu( {
+				title: 'Another One',
+				content:
+					'<!-- wp:navigation-link {"label":"Another Item","type":"custom","url":"http://www.wordpress.org/","kind":"custom"} /-->',
+			} );
+
+			const editorSidebar = page.getByRole( 'region', {
+				name: 'Navigation',
+			} );
+
+			await editorSidebar
+				.getByRole( 'button', {
+					name: 'Navigation',
+				} )
+				.click();
+
+			// Wait for list of Navigations to appear.
+			await expect(
+				editorSidebar.getByRole( 'heading', {
+					name: 'Navigation',
+					level: 1,
+				} )
+			).toBeVisible();
+
+			await editorSidebar
+				.getByRole( 'button', {
+					name: 'Primary Menu',
+				} )
+				.click();
+
+			await expect( page ).toHaveURL(
+				`wp-admin/site-editor.php?postId=${ createdMenu?.id }&postType=wp_navigation`
+			);
+
+			// Wait for list of Navigations to appear.
+			editorSidebar.getByRole( 'heading', {
+				name: 'Primary Menu',
+				level: 1,
+			} );
+
+			// Switch to editing the Navigation Menu
+			await editorSidebar
+				.getByRole( 'link', {
+					name: 'Edit',
+				} )
+				.click();
+		} );
+
+		await test.step( 'Check Navigation block is present and locked', async () => {
+			// Open List View.
+			await pageUtils.pressKeys( 'access+o' );
+
+			const listView = page
+				.getByRole( 'region', {
+					name: 'List View',
+				} )
+				.getByRole( 'treegrid', {
+					name: 'Block navigation structure',
+				} );
+
+			await expect( listView ).toBeVisible();
+
+			const navBlockNode = listView.getByRole( 'link', {
+				name: 'Navigation (locked)',
+				exact: true,
+			} );
+
+			// The Navigation block should be present and locked.
+			await expect( navBlockNode ).toBeVisible();
+
+			// The block should have no options menu.
+			await expect(
+				listView.getByRole( 'button', {
+					name: 'Options for Navigation',
+					exact: true,
+				} )
+			).toBeHidden();
+
+			// Select the Navigation block.
+			await navBlockNode.click();
+		} );
+
+		await test.step( 'Check Navigation block has no controls other than editable list view', async () => {
+			// Open the document settings sidebar
+			await editor.openDocumentSettingsSidebar();
+
+			const sidebar = page.getByRole( 'region', {
+				name: 'Editor settings',
+			} );
+
+			await expect( sidebar ).toBeVisible();
+
+			// Check that the `Menu` control is visible.
+			// This is effectively the contents of the "List View" tab.
+			await expect(
+				sidebar.getByRole( 'heading', { name: 'Menu', exact: true } )
+			).toBeVisible();
+
+			// Check the standard tabs are not present.
+			await expect(
+				sidebar.getByRole( 'tab', { name: 'List View' } )
+			).toBeHidden();
+			await expect(
+				sidebar.getByRole( 'tab', { name: 'Settings' } )
+			).toBeHidden();
+			await expect(
+				sidebar.getByRole( 'tab', { name: 'Styles' } )
+			).toBeHidden();
+		} );
+	} );
+} );