testing-patterns

Run the test_runner.py script with the --coverage flag against your project path. It detects Jest or Vitest from package.json dependencies and executes npx jest --coverage or npx vitest run --coverage automatically.

Use unit tests for pure functions and business logic, integration tests for APIs and database queries, and E2E tests only for critical user flows. Follow the testing pyramid: many fast unit tests, some integration tests, few slow E2E tests.

Mock external APIs, databases, time, randomness, and network calls to keep unit tests fast and isolated. Do not mock the code under test, pure functions, or simple in-memory dependencies.

Yes, the runner detects Python projects via pyproject.toml or requirements.txt and runs python -m pytest -v. With the coverage flag it executes pytest with --cov and --cov-report=term-missing.

Detection fails when the project lacks a package.json with a test script or recognized dependencies, and has no pyproject.toml or requirements.txt. Add a test script or install Jest, Vitest, or pytest to enable detection.