Add e2e test for activating themes in site editor (#60707)

Co-authored-by: ntsekouras <ntsekouras@git.wordpress.org>
Co-authored-by: draganescu <andraganescu@git.wordpress.org>

test/e2e/specs/site-editor/activate-theme.spec.js

@@ -0,0 +1,53 @@
+/**
+ * WordPress dependencies
+ */
+const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
+
+test.describe( 'Activate theme', () => {
+	test.beforeEach( async ( { admin, page } ) => {
+		await admin.visitAdminPage( 'themes.php' );
+		await page.getByLabel( 'Live Preview Emptytheme' ).click();
+	} );
+	test.afterEach( async ( { requestUtils } ) => {
+		await requestUtils.activateTheme( 'twentytwentyone' );
+	} );
+	test( 'activate block theme when live previewing from sidebar save button', async ( {
+		admin,
+		page,
+	} ) => {
+		await page
+			.getByRole( 'button', { name: 'Activate Emptytheme' } )
+			.click();
+		await page
+			.getByRole( 'button', { name: 'Activate', exact: true } )
+			.click();
+		await expect(
+			page.getByRole( 'button', { name: 'Dismiss this notice' } )
+		).toContainText( 'Site updated' );
+		await admin.visitAdminPage( 'themes.php' );
+		await expect( page.getByLabel( 'Customize Emptytheme' ) ).toBeVisible();
+	} );
+	test( 'activate block theme when live previewing in edit mode', async ( {
+		editor,
+		admin,
+		page,
+	} ) => {
+		// Wait for the loading to complete.
+		await expect( page.locator( '.edit-site-canvas-loader' ) ).toHaveCount(
+			0
+		);
+		await editor.canvas.locator( 'body' ).click();
+		await page
+			.getByRole( 'region', { name: 'Editor top bar' } )
+			.getByRole( 'button', { name: 'Activate Emptytheme' } )
+			.click();
+		await page
+			.getByRole( 'button', { name: 'Activate', exact: true } )
+			.click();
+		await expect(
+			page.getByRole( 'button', { name: 'Dismiss this notice' } )
+		).toContainText( 'Site updated' );
+		await admin.visitAdminPage( 'themes.php' );
+		await expect( page.getByLabel( 'Customize Emptytheme' ) ).toBeVisible();
+	} );
+} );