Even more performance measurements
## Measuring long tasks in our code ```js // Test for long tasks test('should capture long tasks on the page', async ({ page }) => { // Function to capture long tasks async function captureLongTasks(durationThreshold) { return page.evaluate((threshold) => { return new Promise((resolve) => { const longTasks = []; const observer = new PerformanceObserver((list) => { for (const entry of list.getEntries()) { if (entry.duration > threshold) { longTasks.push(entry); } } }); observer.observe({ entryTypes: ['longtask'] }); // Assuming the long tasks will be captured within a certain time frame setTimeout(() => { observer.disconnect(); resolve(longTasks); }, 5000); // Adjust the timeout as needed }); }, durationThreshold); } // Capture long tasks // 50ms as the threshold for long tasks const longTasks = await captureLongTasks(50); // Assertions with expect expect(longTasks).toBeInstanceOf(Array); // Expect no more than 5 long tasks expect(longTasks.length).toBeLessThanOrEqual(5); }); ``` ## Does the page generate errors if external resources don't load? ```js test("Tests if page will work when 3rd party resources are blocked", async ({ page }) => { page.route("**", (route) => { const requestURL = route.request().url() if (requestURL.match(/http:\/\/localhost:8080/)) { route.continue() } else { route.abort() } }) // monitor emitted page errors const errors = [] page.on("pageerror", (error) => { errors.push(error) }) await page.goto("http://localhost:8080") console.log(errors) expect(errors.length).toBe(0) }) ``` ## The impact of service workers on performance measurement ## The impact of the device you're testing with