trezor-suite/skills/tests-native.md

Writing Native Tests (TDD)

This skill enforces Test-Driven Development (TDD) practices for suite-native packages and ensures proper usage of the @suite-native/test-utils package.

Core Principles

1. Test-First Development

• ALWAYS write tests before implementing features in suite-native packages.
• Follow the Red-Green-Refactor cycle:
  1. Red: Write a failing test that describes the desired behavior. Run test to confirm it fails for the right reason (e.g., "Cannot find element" or "Expected value to be X but got Y").
  2. Green: Write the minimum code to make the test pass. Run test to confirm it passes.
  3. Refactor: Clean up the code while keeping tests green. Run test to confirm it still passes after refactoring.

2. Writing tests

• Focus on testing behavior and user interactions, not implementation details.
• Use translation IDs instead of literal text to avoid breaking tests with Crowdin updates.
• Follow arrange-act-assert pattern for test structure.

3. Use @suite-native/test-utils Package

• REQUIRED: Use @suite-native/test-utils for all suite-native testing.
• NEVER import directly from @testing-library/react-native.
• The test-utils package provides all necessary utilities and proper test setup.

Checklist

Before submitting code, ensure:

• Tests were written BEFORE implementation
• Using @suite-native/test-utils (not direct @testing-library/react-native)
• Correct render function used (renderWithStoreProvider, renderWithBasicProvider, render)
• Translation IDs used instead of literal strings
• Fixtures are properly typed
• Tests focus on behavior, not implementation
• All interactions use userEvent
• Tests follow naming conventions (.comp.test.tsx, .hook.test.ts)
• All tests pass locally