Automating Login via OAuth2 with Playwright

In modern web applications, traditional login forms are increasingly being replaced by secure and flexible authentication protocols like OAuth2. OAuth2 allows users to authenticate via third-party providers such as Google, Facebook, GitHub, or Microsoft. For testers and developers automating workflows using Playwright, handling OAuth2 logins can be a bit more complex than standard username-password logins.

In this blog, we’ll explore how to automate login via OAuth2 with Playwright, including key concepts, a step-by-step approach, and best practices to securely handle authentication flows.

Understanding OAuth2 Login Flows

OAuth2 is an authorization framework that allows third-party applications to obtain limited access to user accounts without sharing passwords. The typical OAuth2 login flow includes:

• User clicks "Login with Google" (or other providers).
• User is redirected to the provider’s login page.
• Upon authentication, the user is redirected back to the application with an authorization token.

This redirection flow and cross-domain behavior pose challenges for test automation tools.

Why Use Playwright?

Playwright is a modern end-to-end testing framework that supports multiple browsers and automates complex user interactions. Its multi-context capabilities and support for handling multiple pages and redirections make it ideal for automating OAuth2 login flows.

Step-by-Step: Automating OAuth2 Login with Playwright

1. Install Playwright

bash

npm install -D @playwright/test

npx playwright install

2. Launch Browser and Navigate to App

Start by launching the browser and navigating to the app where the OAuth login button exists.

javascript

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

(async () => {

  const browser = await chromium.launch({ headless: false });

  const context = await browser.newContext();

  const page = await context.newPage();

  await page.goto('https://yourapp.com/login');

})();

3. Click on OAuth Login Button

javascript

await page.click('text=Login with Google');  // Replace with actual selector

4. Handle Redirection to Provider

Playwright will open a new popup or redirect the current tab to the OAuth provider’s login page. You must:

• Detect the new page
• Interact with the OAuth login form

javascript

const [popup] = await Promise.all([

  context.waitForEvent('page'),

  page.click('text=Login with Google'),

]);

await popup.fill('input[type="email"]', 'your-email@example.com');

await popup.click('button:has-text("Next")');

await popup.fill('input[type="password"]', 'your-password');

await popup.click('button:has-text("Next")');

await popup.waitForNavigation();

5. Wait for Redirection Back

Once authenticated, OAuth redirects back to your app. Playwright automatically tracks this.

javascript
await page.waitForNavigation();
console.log('Login successful, redirected to app');

Best Practices

• Avoid using real credentials in scripts. Use environment variables or secure credential storage.
• Use test accounts with limited permissions to avoid exposing sensitive data.
• Mock OAuth tokens if the provider offers a sandbox environment.
• For CI/CD, consider generating auth tokens manually and injecting them into session storage or cookies instead of performing a UI login each time.

Alternative: API-based Authentication

If possible, skip the UI login entirely by:

• Generating a valid OAuth2 access token using client credentials.
• Setting the token in local/session storage or request headers.
• This approach is faster, more secure, and more stable in automated pipelines.

Conclusion

Automating login via OAuth2 with Playwright requires handling multiple tabs, dynamic elements, and redirection flows. With Playwright’s powerful browser control and event-handling capabilities, you can streamline even complex authentication processes. Whether for testing or browser automation, integrating OAuth2 login with Playwright ensures secure, scalable, and realistic end-to-end test coverage for modern web applications.

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