test: Fix flaky demo test (#25076)

Author: shortstacked

packages/testing/playwright/pages/DemoPage.ts

@@ -1,14 +1,10 @@
 import { BasePage } from './BasePage';
 
 export class DemoPage extends BasePage {
-	async visitDemoPage(theme?: 'dark' | 'light') {
+	async goto(theme?: 'dark' | 'light') {
 		const query = theme ? `?theme=${theme}` : '';
 		await this.page.goto('/workflows/demo' + query);
-		await this.getBody().waitFor({ state: 'visible' });
-		await this.page.evaluate(() => {
-			// @ts-expect-error - this is a custom property added by the demo page
-			window.preventNodeViewBeforeUnload = true;
-		});
+		await this.page.getByTestId('canvas-background').waitFor({ state: 'visible' });
 	}
 
 	/**

packages/testing/playwright/tests/e2e/app-config/demo.spec.ts

@@ -17,14 +17,14 @@ test.describe('Demo', () => {
 	});
 
 	test('can import template', async ({ n8n }) => {
-		await n8n.demo.visitDemoPage();
+		await n8n.demo.goto();
 		expect(await n8n.notifications.getAllNotificationTexts()).toHaveLength(0);
 		await n8n.demo.importWorkflow(simpleWorkflow);
 		await expect(n8n.canvas.getCanvasNodes()).toHaveCount(3);
 	});
 
 	test('can import workflow with pin data', async ({ n8n }) => {
-		await n8n.demo.visitDemoPage();
+		await n8n.demo.goto();
 		await expect(n8n.canvas.canvasPane()).toBeVisible();
 		await n8n.demo.importWorkflow(workflowWithPinned);
 		await expect(n8n.canvas.getCanvasNodes()).toHaveCount(2);
@@ -34,13 +34,13 @@ test.describe('Demo', () => {
 	});
 
 	test('can override theme to dark', async ({ n8n }) => {
-		await n8n.demo.visitDemoPage('dark');
+		await n8n.demo.goto('dark');
 		await expect(n8n.demo.getBody()).toHaveAttribute('data-theme', 'dark');
 		expect(await n8n.notifications.getAllNotificationTexts()).toHaveLength(0);
 	});
 
 	test('can override theme to light', async ({ n8n }) => {
-		await n8n.demo.visitDemoPage('light');
+		await n8n.demo.goto('light');
 		await expect(n8n.demo.getBody()).toHaveAttribute('data-theme', 'light');
 		expect(await n8n.notifications.getAllNotificationTexts()).toHaveLength(0);
 	});