How to Generate Lighthouse Reports With Playwright on TestMu AI
If you run Playwright tests and want to measure page quality in the same run, you can generate Lighthouse reports on TestMu AI without a separate audit step. A Lighthouse report scores performance, accessibility, SEO, and best practices using Google Lighthouse, the open-source auditing tool from Google. You add the Playwright Lighthouse Library to your project and call the lighthouseReport action from within a test to produce the report on the cloud machine.
Lighthouse reports are supported on Chrome, MicrosoftEdge, and Chromium browsers.
The code sample for generating Lighthouse performance metrics in a Playwright test is available in the TestMu AI GitHub repository. Download or clone the repository to run the tests as shown. 
View on GitHub
Prerequisites
Before you write the test, install the library and enable Lighthouse in your project environment.
-
Ensure that you have the Playwright Lighthouse Library installed in your web project.
Verifiednpm install playwright-lighthouse -
Export the LIGHTHOUSE_LAMBDATEST environment variable to your project environment.
Verifiedexport LIGHTHOUSE_LAMBDATEST='true'
Write Your Test Script
Add the lighthouseReport action to a Playwright test to capture Lighthouse metrics for a target URL during the run.
Generating a Lighthouse report within the test can increase the test duration. Generate Lighthouse reports only in the tests that need them.
The JavaScript snippet below runs the lighthouseReport action against a URL from inside the test.
await page.evaluate(_ => {}, `lambdatest_action: ${JSON.stringify({
action: 'lighthouseReport',
arguments: { url: 'https://www.example.com' }
})}`)
Generate Reports for Authenticated Pages
Use this approach to audit pages that require a login by passing an authentication token to Lighthouse. It lets you measure performance, accessibility, and SEO for restricted pages in your Playwright tests. This feature is supported on Windows and macOS platforms only.
VerifiedThis feature is only supported on Windows and macOS platforms.
- Windows
- macOS
await page.evaluate(() => {}, `lambdatest_action: ${JSON.stringify({
action: 'lighthouseReport',
arguments: { url: 'https://www.example.com',
args: `--extra-headers
${JSON.stringify({ authtoken: "YOUR_AUTH_TOKEN" })}`
} })}` );
await page.evaluate(() => {}, `lambdatest_action: ${JSON.stringify({
action: 'lighthouseReport',
arguments: { url: 'https://www.example.com',
args: '--extra-headers
"{\\"authtoken\\": \\"YOUR_AUTH_TOKEN\\"}"'
} })}`);
Sample Test Script
The script below runs Playwright automation with the Lighthouse library on TestMu AI. It navigates to the DuckDuckGo search engine, searches for the term "Playwright", then runs a Lighthouse audit on https://duckduckgo.com with defined performance thresholds and report formats.
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Trigger Your Test on TestMu AI
With the script ready, set your credentials and run the test so the report is generated on the TestMu AI cloud machine.
Set Up Your Authentication
You need your TestMu AI credentials to run automation scripts on TestMu AI. To obtain access credentials, purchase a TestMu AI plan or open the TestMu AI Automation Dashboard. Then set your TestMu AI Username and Access Key in environment variables with the following commands.
- Linux / MacOS
- Windows
export LT_USERNAME=undefined
export LT_ACCESS_KEY=undefined
set LT_USERNAME=undefined
set LT_ACCESS_KEY=undefined
Run Your Test
Run the following command in the terminal, replacing the placeholder with the path to your test file.
Verifiednode RELATIVE_PATH_OF_YOUR_TEST_FILE
View Your Test Results
To review runs that use the Playwright Lighthouse Library, open the TestMu AI Web Automation Dashboard.
Related Playwright Guides
Continue with the guides below to build out your Playwright test coverage on TestMu AI.
- Get started with Playwright testing on TestMu AI covers the base setup for cloud runs.
- Set up Playwright test execution on TestMu AI walks through configuring a cloud run.
- Configure Playwright capabilities lists every capability you can set for a test.
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