Use when creating, writing, fixing, or reviewing tests in a Flutter project. Covers unit tests, widget tests, integration tests, Riverpod provider testing, and Mockito mocking. Provides Given-When-Then patterns, layer isolation strategies, and test setup for GetIt, SharedPreferences, and FakeDatabas

Flutter Tester Requirements Flutter project with flutter test dependency Works with Riverpod, Mockito, and GetIt Run dart run build runner build to generate mocks after adding @GenerateMocks annotations Compatible with FVM ( fvm flutter test instead of flutter test ) Overview Test each architectural layer in isolation using Given When Then structure. Always test both success and error paths. Never mock providers — override their dependencies instead. Reference Files Load the relevant file based on what you're testing: What you're testing Reference file Repository, DAO, Service logic references/layer testing patterns.md Widget UI, interactions, dialogs, navigation references/widget testing guide.md Riverpod provider state, mutations, lifecycle references/riverpod testing guide.md Core Principles 1. Layer Isolation Test each layer against its own mocked dependencies: Layer What to test What to mock Repository Data coordination between sources DAOs, APIs, Logger DAO Database CRUD operations Use real in memory DB, mock Logger Provider State management and transitions Services, Repositories Service Business logic and workflows Repositories, Network clients Widget UI behaviour and interactions Provider dependencies (via overrides) 2. Given When Then Structure 3. Test Organisation Standard Test Setup Generate Mocks Run dart run build runner build after modifying @GenerateMocks . Register with GetIt Fakes vs Mocks Fakes ( class FakeLogger extends ILogger ) — silent stubs; use when you don't need to verify calls Mocks ( MockILogger ) — use when you need when() , verify() , or thenThrow() Quick Reference Scenario Key pattern Test a repository Mock DAO + API → inject into repository constructor Test a DAO FakeDatabase or openInMemoryDatabase() in setUp, delete table in tearDown Test a Riverpod provider createContainer(overrides: [serviceProvider.overrideWith(...)]) Test a widget Set screen size, use find.byKey() , call pumpAndSettle() Test a loading state Use Completer , pump() to assert loading, complete, pump() again Test platform specific UI debugDefaultTargetPlatformOverride = TargetPlatform.iOS — reset after Test GoRouter navigation FakeGoRouter + MockGoRouterProvider Running Tests Common Mistakes Mistake Fix Mocking a provider directly Override its dependencies: provider.overrideWith(...) Missing GetIt.I.reset() in tearDown Tests pollute each other — always reset await Future.delayed() in tests Use await tester.pumpAndSettle() or Completer instead Finding widgets by text string Use find.byKey(const Key('name')) — stable across text changes No screen size in widget tests Add tester.view.physicalSize = const Size(1000, 1000) Not resetting debugDefaultTargetPlatformOverride Set to null at the end of the test tearDown() without a lambda Write tearDown(() async { ... }) not tearDown() async { ... } Test Checklist Setup & Mocking: [ ] Dependencies mocked (not providers) [ ] SharedPreferences mocked if used [ ] GetIt.I.reset() in tearDown [ ] Streams closed in tearDown [ ] Controllers disposed in tearDown Widget Tests: [ ] Keys added to source widgets and used in find.byKey() [ ] Screen size set ( physicalSize + devicePixelRatio ) [ ] Platform overrides reset ( debugDefaultTargetPlatformOverride = null ) [ ] Navigation verified if applicable Test Coverage: [ ] Success and failure paths covered [ ] Edge cases tested (null, empty, max values) [ ] Loading and error states tested [ ] Async handled correctly (no Future.delayed ) Code Quality: [ ] Given When Then naming used [ ] verify() or verifyNever() where appropriate [ ] Tests are isolated and deterministic

flutter-tester