testing-patterns_skill

Overview

This skill documents pragmatic testing patterns for Flutter/Dart projects: unit, repository, controller, widget, integration, and golden tests with clear mocking strategies. It presents repeatable examples that fit enterprise Rails-aligned workflows but remain portable across any codebase. The focus is on reliable, maintainable tests that support CI quality gates and multi-agent orchestration.

How this skill works

The skill outlines what to inspect and how to mock at each layer: use-case and controller units with mock use cases/repositories, repository tests that toggle network/local paths, widget tests that inject mocked controllers, integration tests driving full flows, and golden tests validating visual output. Each pattern shows arrange-act-assert structure, verification of interactions, and cleanup steps to avoid test pollution.

When to use it

• Unit tests for domain logic and small data transformations
• Repository tests when behavior depends on network/local sources and caching
• Controller tests to validate state management and error handling
• Widget tests for UI logic with injected mock controllers
• Integration tests for critical user flows across screens and services
• Golden tests to lock visual regressions for key components

Best practices

• Keep unit tests focused: one behavior per test and explicit arrange-act-assert
• Prefer mocks for external dependencies and verify interactions to catch regressions
• Test both online and offline repository branches and cache behavior
• Use dependency injection (or service locators) to inject mocks in widget tests and clean up after each test
• Limit golden tests to stable components and run them in consistent environments
• Run integration tests selectively in CI and keep them deterministic by avoiding flaky waits

Example use cases

• Validate a GetUser use-case returns domain entities and handles failures
• Ensure repository fetches remote data when online and returns cached data when offline
• Confirm controller toggles loading and error states correctly for UI consumers
• Assert UserPage shows loader, data, or error by injecting a mocked controller
• Run a full login flow in an integration test to verify end-to-end navigation
• Capture a UserCard golden to prevent visual regressions in the app shell