Visual Regression Testing for Drupal using Playwright step by step guide

3 min readJul 3, 2024

Visual regression testing with Playwright for Drupal involves capturing screenshots of your Drupal site’s pages and comparing them over time to detect unintended visual changes. Here’s a step-by-step guide to set up and execute visual regression tests using Playwright with Drupal:

Step 1: Install Node.js and npm

Ensure Node.js and npm are installed on your system. You can download and install them from nodejs.org.

Step 2: Set Up a Drupal Site

Install Drupal 10: Set up a local instance of Drupal 10 for testing purposes. You can download Drupal from drupal.org or use Composer to create a new project.
Configure Drupal: Configure your Drupal site with necessary modules, themes, and content relevant to your testing scenarios.

Step 3: Install Playwright

Install Playwright: Open your terminal and install Playwright globally:

npm install -g playwright

Create a New Playwright Project: Create a new directory for your Playwright project and initialize it:

mkdir playwright-tests 
cd playwright-tests 
npm init -y

Step 4: Install Playwright for Node.js

Install Playwright for Node.js: Install Playwright for Node.js as a dependency in your project:

npm install --save-dev playwright

Step 5: Write Playwright Test Scripts

Create a new JavaScript file (e.g., visual-regression-test.js) where you will write your Playwright test scripts to capture screenshots and perform visual regression testing.

Here’s a basic example:

const { chromium } = require('playwright');

(async () => {
  // Launch browser
  const browser = await chromium.launch();

  // Create a new browser context
  const context = await browser.newContext();

  // Create a new page
  const page = await context.newPage();

  try {
    // Adjust viewport size as needed
    await page.setViewportSize({ width: 1200, height: 800 });

    // Navigate to your Drupal site
    await page.goto('http://localhost:8000');

    // Example: Capture screenshot of the homepage
    await page.screenshot({ path: 'screenshots/homepage.png' });

    // Example: Navigate to a specific page and capture screenshot
    await page.goto('http://localhost:8000/about');
    await page.screenshot({ path: 'screenshots/about.png' });

    console.log('Screenshots captured successfully.');
  } catch (error) {
    console.error('Error capturing screenshots:', error);
  } finally {
    // Close browser
    await browser.close();
  }
})();

Replace http://localhost:8000 with the URL of your local Drupal 10 site.

Step 6: Run Playwright Tests

Run the Test Script: Execute your Playwright test script to capture screenshots and perform visual regression testing:

node visual-regression-test.js

Review Screenshots: After running the tests, review the screenshots generated in the screenshots directory (create this directory if it doesn't exist). These screenshots represent the baseline images.

Step 7: Set Up Visual Regression Comparison

To detect visual changes over time, you can use tools like BackstopJS or integrate with visual testing services such as Applitools. These tools allow you to compare screenshots captured during different test runs and identify any discrepancies.

Step 8: Integrate with Continuous Integration (CI)

You can integrate Playwright tests into your CI/CD pipeline (e.g., using GitHub Actions, GitLab CI) to automate visual regression testing on every code change or deployment.

Additional Considerations

Viewport Sizes: Adjust viewport sizes in your Playwright script to match common device resolutions for responsive testing.
Handling Dynamic Content: Consider dynamic content on Drupal pages (e.g., user-specific content, time-dependent elements) that may affect visual comparisons.

By following these steps, you can effectively set up and execute visual regression testing using Playwright for your Drupal 10 site, ensuring that UI changes are detected and managed efficiently during development and maintenance phases.

Certainly! If you encounter any issues or have further questions about setting up visual regression testing with Playwright for your Drupal site, feel free to connect with me. I’m here to help! Just describe the problem or the specific area you’re facing difficulty with, and I’ll provide guidance or clarification to assist you further.