Migrate flaky PostPublishButton e2e tests to Playwright (#52285)

* Migrate flaky PostPublishButton e2e tests to Playwright
* Remove old test file
* Fix locators
* Try deferring the requests

test/e2e/specs/editor/various/publish-button.spec.js

@@ -0,0 +1,103 @@
+/**
+ * WordPress dependencies
+ */
+const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
+
+function defer() {
+	let resolve;
+	const deferred = new Promise( ( res ) => {
+		resolve = res;
+	} );
+	deferred.resolve = resolve;
+	return deferred;
+}
+
+test.describe( 'Post publish button', () => {
+	test( 'should be disabled when post is not saveable', async ( {
+		admin,
+		page,
+	} ) => {
+		await admin.createNewPost();
+		await expect(
+			page
+				.getByRole( 'region', { name: 'Editor top bar' } )
+				.getByRole( 'button', { name: 'Publish' } )
+		).toBeDisabled();
+	} );
+
+	test( 'should be disabled when post is being saved', async ( {
+		admin,
+		editor,
+		page,
+	} ) => {
+		await admin.createNewPost();
+		await editor.canvas
+			.getByRole( 'textbox', {
+				name: 'Add title',
+			} )
+			.fill( 'Test post' );
+
+		const topBar = page.getByRole( 'region', { name: 'Editor top bar' } );
+		await expect(
+			topBar.getByRole( 'button', { name: 'Publish' } )
+		).toBeEnabled();
+
+		const postId = new URL( page.url() ).searchParams.get( 'post' );
+		const deferred = defer();
+
+		await page.route(
+			( url ) =>
+				url.searchParams.has(
+					'rest_route',
+					encodeURIComponent( `/wp/v2/posts/${ postId }` )
+				),
+			async ( route ) => {
+				await deferred;
+				await route.continue();
+			}
+		);
+
+		await topBar.getByRole( 'button', { name: 'Save draft' } ).click();
+		await expect(
+			topBar.getByRole( 'button', { name: 'Publish' } )
+		).toBeDisabled();
+		deferred.resolve();
+	} );
+
+	test( 'should be disabled when metabox is being saved', async ( {
+		admin,
+		page,
+		requestUtils,
+	} ) => {
+		await requestUtils.activatePlugin( 'gutenberg-test-plugin-meta-box' );
+		await admin.createNewPost();
+		await page
+			.getByRole( 'textbox', {
+				name: 'Add title',
+			} )
+			.fill( 'Test post' );
+
+		const topBar = page.getByRole( 'region', { name: 'Editor top bar' } );
+		await expect(
+			topBar.getByRole( 'button', { name: 'Publish' } )
+		).toBeEnabled();
+
+		const deferred = defer();
+
+		await page.route(
+			( url ) => url.searchParams.has( 'meta-box-loader', 1 ),
+			async ( route ) => {
+				await deferred;
+				await route.continue();
+			}
+		);
+
+		await topBar.getByRole( 'button', { name: 'Save draft' } ).click();
+		await expect(
+			topBar.getByRole( 'button', { name: 'Publish' } )
+		).toBeDisabled();
+		deferred.resolve();
+
+		await requestUtils.deactivatePlugin( 'gutenberg-test-plugin-meta-box' );
+	} );
+} );