The tests subject contains utilities, helpers, and infrastructure to support automated testing across docs.github.com. This includes test helpers, mock servers, schema validation, and shared testing patterns.

This subject is responsible for:

• Test utilities and helper functions shared across subjects
• Mock server infrastructure for integration tests
• Schema validation utilities (AJV)
• Test data and fixtures management
• Vitest configuration and setup
• TypeScript declarations for test tooling
• Shared testing patterns and conventions

Tests are written using Vitest for unit and integration tests, and Playwright for end-to-end browser tests.

• lib/validate-json-schema.ts - AJV validator factory for JSON schema validation
• mocks/start-mock-server.ts - Creates mock HTTP server for integration tests
• helpers/e2etest.ts - Utilities for end-to-end testing scenarios
• vitest.setup.ts - Global Vitest configuration and hooks

Test-only dependencies are optional to keep standard installs faster:

npm ci --include=optional

Important: Do NOT run npm test without a path argument. Tests must be run per-suite because different suites require different environment variables. Running all tests at once will produce many false failures.

Important: Run npm run build before running tests. Many test suites depend on Next.js build artifacts. Without a build, tests may fail with Could not find a production build or other confusing errors.

Always target the specific suite for the code you changed:

# By directory (recommended)
npm test -- src/search/tests/

# Single test file
npm test -- src/versions/tests/versions.ts

Some suites require environment variables or tests will fail with 404s or content mismatches. These suites have dedicated npm scripts that set the required variables automatically:

npm run test:article-api
npm run test:changelogs
npm run test:fixtures
npm run test:landings
npm run test:languages    # requires Elasticsearch running
npm run test:search       # requires Elasticsearch running

For the content-linter suite, you can optionally scope to changed files:

DIFF_FILES="content/foo.md content/bar.md" \
  npm test -- src/content-linter/tests/

All other suites (e.g., versions, redirects, rest, frame, content-render) can be run without special environment variables.

The search and languages test suites require Elasticsearch on localhost:9200. To start it with Docker:

docker run -d \
  -p 127.0.0.1:9200:9200 \
  -e 'discovery.type=single-node' \
  -e 'xpack.security.enabled=false' \
  --name es-local \
  docker.elastic.co/elasticsearch/elasticsearch:8.12.0

Wait for it to be ready, then index the test fixtures:

curl --silent --fail http://localhost:9200  # verify ES is up
ELASTICSEARCH_URL=http://localhost:9200/ npm run index-test-fixtures

After that, npm run test:search and npm run test:languages will work.

See .github/workflows/test.yml for the full CI matrix and per-suite configuration.

Continuously re-runs tests on file changes:

npm test -- --watch

By default, console.log is suppressed. To see output:

npm test -- <TEST_NAME> --silent=false

Some tests require a production build:

npm run build
npm test -- src/<suite>/tests/

Error: Could not find a production build means you need to run npm run build.

• Vitest - Test runner and assertion library
• Playwright - Browser automation for E2E tests
• AJV - JSON schema validation
• Mock server libraries for HTTP mocking

• Fixture content in src/fixtures/
• Schema files in helpers/schemas/
• Mock responses in mocks/

Tests that make HTTP requests to localhost:4000:

• Vitest automatically starts/stops server via hooks
• Disable with START_VITEST_SERVER=false for manual server control

Manual server for debugging:

# Terminal 1
NODE_ENV=test PORT=4000 tsx src/frame/server.ts

# Terminal 2
START_VITEST_SERVER=false vitest src/versions/tests

• src/fixtures - Fixture-based testing with minimal content
• All subjects with /tests/ directories - Test consumers
• CI workflows in .github/workflows/ - Automated test execution

• Fixture content - Fixture-based testing patterns
• Playwright E2E tests - Headless browser testing

• Team: Docs Engineering

Unit tests - Test individual functions/modules:

import { describe, test, expect } from 'vitest'

describe('myFunction', () => {
  test('returns expected value', () => {
    expect(myFunction('input')).toBe('output')
  })
})

Integration tests - Test HTTP endpoints:

import { get } from '@/tests/helpers/e2etest'

test('GET /search returns results', async () => {
  const res = await get('/search?query=test')
  expect(res.statusCode).toBe(200)
})

Playwright tests - Browser automation:

test('search works in browser', async ({ page }) => {
  await page.goto('/search')
  await page.fill('input[name="query"]', 'test')
  // ...assertions
})

Middleware errors are suppressed by default in tests. To see full errors:

export DEBUG_MIDDLEWARE_TESTS=true
vitest src/shielding/tests

npm run lint

• Optional dependencies must be installed for local testing
• Some tests require production build (npm run build)
• Server startup/shutdown adds overhead to test runs
• Fixtures may lag behind actual content structure

Tests should be co-located with their subject:

• ✅ src/search/tests/api-search.ts
• ✅ src/versions/tests/middleware.ts
• ❌ src/tests/search-tests.ts (wrong - not in subject)

Shared utilities belong in src/tests/:

• Helper functions used across subjects
• Mock servers and fixtures
• Schema validation utilities
• Test infrastructure

1. Create a file in src/tests/helpers/
2. Export reusable functions
3. Document usage with JSDoc
4. Add tests for the helper itself
5. Import in test files across subjects

Tests run automatically in GitHub Actions on pull requests and merge groups. Each test suite runs as a separate matrix job with its own environment variables—see .github/workflows/test.yml for the full configuration. Locally, always target a specific suite rather than running all tests at once.

Tests fail with missing build: Run npm run build before tests.

Tests hang or timeout: Check if server started correctly. Use DEBUG_MIDDLEWARE_TESTS=true.

Flaky tests:

• Check for race conditions
• Ensure proper test isolation
• Verify mocks are properly reset

Mock server issues: Check src/tests/mocks/start-mock-server.ts is running and configured correctly.