klh-testing-patterns

Create a getMockX function that returns default values and accepts a Partial overrides object, then spread overrides last. This keeps test data DRY and consistent across tests while allowing per-test customization of specific properties.

Use jest.mock with the module path, optionally passing a factory that returns jest.fn() implementations. Access the mock via jest.requireMock and set return values with mockReturnValue inside each test.

Write a failing test first, run it to confirm it fails cleanly with a meaningful message, then write the minimal implementation to pass, and refactor after green. A test that passes before implementation indicates a broken assertion.

Yes, the patterns use @testing-library/react-native with a custom render function that wraps components in required providers like ThemeProvider. Queries, fireEvent, and waitFor handle rendering, interaction, and async assertions.

Asserting that a mock was called only verifies the mock, not the actual behavior users see. Prefer assertions on rendered output, such as checking that expected text appears on screen, to catch real bugs.