Dart & Flutter Testing

Testing fundamentals for Dart and Flutter projects — unit tests, widget tests, and golden file tests — using package:test, package:flutter_test, package:mocktail, and package:bloc_test.

Core Standards

Apply these standards to ALL test work:

• Descriptive test names — verbose, readable names that describe the behavior; never 'works' or 'renders'
• Hierarchical group/test structure that reads as natural sentences — top-level group for the class, nested group for the method, test for the behavior (e.g., UserRepository → getUser → returns User when API succeeds)
• String interpolation for type references — use 'returns $User' not 'returns User' so renames propagate automatically
• Private mocks per file — declare class _MockX extends Mock implements X {} with underscore prefix to prevent cross-file coupling
• Contained test setup within groups — all setUp/tearDown calls live inside a group, never at the top level of main()
• Initialize mutable objects in setUp() with late — declare late MyDep dep; then assign in setUp so each test gets a fresh instance
• No shared mutable state between tests — never use static members, global variables, or top-level final instances that persist across tests
• Use package:mocktail — never package:mockito
• Constant test tags — use an abstract class TestTag with static const fields; never pass raw string literals as tags
• Test behavior, not properties — widget tests focus on functional outcomes; static visual properties validated via golden tests
• Use pumpApp test helper — wrap widgets via shared helper in test/helpers/pump_app.dart; never inline pumpWidget(MaterialApp(...))