Testing Strategy

• Test Pyramid: More unit and widget tests, fewer integration tests. Unit tests are fastest and cheapest.

• Mirror Test Rule: 100% logic and widget coverage. No code without a test.

• Mirror Organization: Test files MUST strictly mirror the lib/ directory structure and end with _test.dart .

• Coverage Targets: Target 100% logic coverage for domain and bloc layers.

• Test Independence: Each test MUST be independent. No shared mutable state between tests.

Unit Testing

• Follow the Arrange-Act-Assert (Given-When-Then) convention for clear and maintainable tests

• Use mocks for dependencies except for lightweight third-party services

• Test business logic in isolation from the UI

• For tests, ensure to create 5 to 8 tests for logical operations with real scenarios

• Mocking Protocol: Use mocktail for all dependency mocking. STRICTLY prohibit using real implementation dependencies in unit tests.

• Pure Logic: Business logic inside BLoCs or UseCases should be extracted to static pure functions for 100% unit test coverage.

Widget Testing

• Write widget tests for all major UI components

• Test user interactions and state changes

• Widget Keys: Use Key('feature_action_id') format on interactive widgets for test access

• Test Localization: Use AppLocalizations (context.l10n ) in widget tests — no hardcoded strings

Integration Testing

• Use IntegrationTestWidgetsFlutterBinding.ensureInitialized() at the start of integration tests

• Interact with widgets via Key (e.g., find.byKey(const ValueKey('increment')) )

• Use pumpAndSettle() to wait for animations and async operations to complete

• Run with: flutter test integration_test/

Test Naming & Structure

• Test Naming: Use string interpolation for test group names: group('$ClassName', not group('ClassName', . This ensures consistency and enables better tooling support.

• Test Grouping: Use group() to organize tests by feature, class, or state for clearer reporting.

• Descriptive Names: Test names should clearly describe what is being tested and why.

Common Test Errors

• A RenderFlex overflowed... — Wrap widget in Expanded or constrain dimensions in test

• Vertical viewport was given unbounded height — Wrap ListView in SizedBox with fixed height in test

• setState called during build — Defer state changes to post-frame callback

Running Tests

• flutter test — Run all unit and widget tests

• flutter test test/path/to/file_test.dart — Run specific test file

• flutter test integration_test/ — Run integration tests

• flutter test --coverage — Run with coverage report