DevTools API Tests

This directory hosts the API tests for DevTools. These tests run DevTools SDK and foundation models against a target page connected over CDP, without needing to spin up the full DevTools frontend UI. We use Mocha as the testing framework.

Writing API tests

Each test receives a state object containing {inspectedPage, universe} as its first parameter:

describe('My API Test', () => {
  it('runs against inspected page', async ({inspectedPage, universe}) => {
    await inspectedPage.goToHtml('<h1>Hello World</h1>');
    // Interact with universe models or inspectedPage...
  });
});

Suite Setup (setup)

Use the setup function inside a describe block to customize suite settings before universe is created:

• creationOptions: Partial Universe.CreationOptions passed to Universe (e.g. hostConfig, inspectorFrontendHost, supportsEmulation, overrideAutoStartModels, settingsCreationOptions).
• targetUrl: Initial URL to navigate the inspected page to FIRST, before the Universe is attached.

describe('Suite with custom hostConfig', () => {
  setup({
    creationOptions: {
      hostConfig: {
        devToolsConsoleInsights: {enabled: true},
      },
    },
    targetUrl: 'https://example.com',
  });

  it('runs with custom config', async ({universe}) => {
    // ...
  });
});

Running API tests

Note that npm run test -- front_end runs unit tests as well. To run API tests specifically, specify a glob matching .test.api.ts files:

npm run test -- "front_end/**/*.test.api.ts"

To run a specific API test file:

npm run test -- front_end/foundation/Universe.test.api.ts

To use out/Debug instead of the default out/Default target directory:

npm run test -- -t Debug "front_end/**/*.test.api.ts"

To run API tests in debug mode:

npm run test -- --debug "front_end/**/*.test.api.ts"

Check the output of npm run test -- --help for an overview of all available options.

Debugging API tests

You can debug the API test process by inspecting the Node.js process that executes the test suite.

Passing --debug to npm run test starts the Node.js runner with inspector support enabled (--inspect). You can attach to the process by:

1. Opening chrome://inspect in Chrome.
2. Clicking Inspect under the Target (Node.js) section or clicking the Node.js icon in any open DevTools window.
3. Setting breakpoints and stepping through test execution in DevTools.