Introduction

Ensuring optimal performance and quality is paramount for web development. This is where automated testing tools like Playwright and Google's Lighthouse come into play.

For software engineers, integrating these tools can assist the testing process, paving the way for more robust, user-friendly web applications.

Understanding Playwright

Playwright is a cutting-edge, open-source framework developed by Microsoft. It's designed to enable end-to-end testing for web applications across all major browsers including Chromium, Firefox, and WebKit.

Its standout features include cross-browser support, native mobile emulation, and the ability to simulate various network conditions. This makes Playwright an invaluable tool for developers aiming to create versatile, cross-platform web applications.

For more information, visit Playwright Documentation.

Exploring Lighthouse

Google's Lighthouse is an automated tool designed for web page quality assessments. It provides audits for performance, accessibility, progressive web applications, and more, offering scores across these domains along with actionable recommendations for improvement.

Lighthouse is instrumental in identifying areas for enhancement in web applications, ensuring they meet the highest standards of quality.

Learn more at Lighthouse Documentation.

The Importance of Combined Testing

Integrating Playwright with Lighthouse brings a holistic approach to testing. While Playwright ensures functional correctness, Lighthouse assesses quality metrics. This combination is crucial for early bug detection, maintaining high performance standards, and ensuring an optimal user experience.

Playwright-lighthouse is a great package for combing these two types of testing and let's dive into using it with a hands on tutorial.

Hands On with Playwright and Playwright-lighthouse

Setting Up Your Environment

To begin, you'll need to set up both playwright and playwright-lighthouse in your project. First, install Playwright using npm:

npm install --save-dev playwright

Then, add playwright-lighthouse:

npm install --save-dev playwright-lighthouse

These installations equip your project with the necessary tools to conduct both Playwright and Lighthouse audits.

Implementing Playwright-Lighthouse Tests

Let’s dive into how you can use these tools together. Consider the following code example:

import { playAudit } from "playwright-lighthouse";
import { test, chromium } from "@playwright/test";

test.describe("audit", () => {
  test("run lighthouse", async () => {
    const browser = await chromium.launch({
      args: ["--remote-debugging-port=9222"],
      headless: true
    });
    const page = await browser.newPage();
    await page.goto("http://localhost:4173/");

    await playAudit({
      page: page,
      thresholds: {
        performance: 50,
        accessibility: 100,
        "best-practices": 100,
        seo: 100
      },
      port: 9222
    });

    await browser.close();
  });
});

In this script:

1. Browser Initialization: We launch Chromium using Playwright, specifying remote debugging and headless mode.

2. Page Navigation: The script navigates to the specified URL.

3. Lighthouse Audit: The playAudit function runs the Lighthouse audit against the page, with specified performance, accessibility, best practices, and SEO thresholds.

In addition to the test code, you can add an execution script to your package.json and configure Playwright with a config (playwright.config.js).

{
    "test:lighthouse": "npx playwright test --project lighthouse"
}

CI/CD Integration

Integrating this setup into a Continuous Integration/Continuous Deployment (CI/CD) pipeline automates the testing process. Each deployment undergoes rigorous quality checks, ensuring consistent performance and adherence to web standards.

For example, I have incorporated lighthouse testing into the CI pipeline for my personal site. A lighthouse test execution will occur on every PR and merge to master. This provides immediate feedback on performance and accessibility that a user will experience.

  analyze:
    # Runs on successful playwright
    needs: [build, test]
    name: lighthouse-test
    # Running on ubuntu-latest, nothing special
    runs-on: ubuntu-latest
    steps:
      # As usual, we simply checkout the project
      - name: Checkout
        uses: actions/checkout@v4
      # Install the latest version of node
      - name: Set up Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "20"
      # Install Yarn (prefered build tool)
      - name: Install Yarn
        run: npm install -g yarn
      # Install project dependencies
      - name: Install dependencies
        run: yarn install --frozen-lockfile
      # Install Playwright browsers
      - name: Install Playwright Browsers
        run: npx playwright install --with-deps
      # Run Lighthouse Playwright tests
      - name: Run Playwright tests
        run: yarn run test:lighthouse

Conclusion

Integrating Playwright with Lighthouse offers a comprehensive approach to web application testing. This powerful combination can significantly enhance the quality and performance of your projects, streamline your workflow, and ensure a superior user experience.

Advantages

• Comprehensive Testing: Offers a complete testing solution combining functional correctness and quality metrics.

• Developer-Friendly: Easy to integrate into existing development workflows.

• Scalable Solution: Equally effective for small and large-scale projects.

Integrating these tools into your software development process marks a step towards more reliable, high-quality web applications. I encourage you to explore these tools and leverage their capabilities in your next project.

Check out the Lighthouse GitHub documentation to learn more. They maintain a cool set of articles on implementation and how to use Lighthouse.