igorescodro/write-unit-tests

Write Unit Tests

Overview

Unit tests in Alkaa are multiplatform-first, fake-based, and structured around a single scenario per test. Tests live in commonTest and run fastest via ./gradlew desktopTest.

Structure

• Given / When / Then — Use comments to separate the three blocks in every test → see references/TEST_EXAMPLES.md
• Backtick names — Start with test if or check if, describe the specific condition and expected outcome
• One scenario per test — Split side effects, error paths, and edge cases into separate tests
• Fakes only — Never mocks for domain interfaces → see references/FAKE_PATTERNS.md for all three fake patterns
• CoroutinesTestDispatcher — Delegate by CoroutinesTestDispatcherImpl() for any coroutine-using test class → see references/TEST_EXAMPLES.md
• ViewModel test setup → see references/TEST_EXAMPLES.md
• Use case / repository test setup → see references/TEST_EXAMPLES.md

Naming

✅ `test if when load tasks fails the error state is returned`
✅ `test if task is updated as completed`
✅ `test if category without name is not added`
❌ testUpdateTask()
❌ test1()

Rules

| Rule | Details | |------|---------| | Fakes over mocks | Only use mocks for Android/Framework types you cannot interface (e.g., Context) | | CoroutinesTestDispatcher | Delegate by CoroutinesTestDispatcherImpl() for any coroutine-using test class | | ViewModel at field level | Construct ViewModel at field level, not inside @BeforeTest | | runTest for suspend | Use = runTest { } for all suspend test bodies | | flow.first() | Collect current state with flow.first() | | require() for narrowing | Use require(state is X) before accessing state-specific properties | | @BeforeTest cleanup | Call clean() on every fake to reset state between tests |

Common Mistakes

| Mistake | Fix | |---------|-----| | Using mocks for domain interfaces | Create a fake implementing the interface | | Forgetting CoroutinesTestDispatcher delegation | Add by CoroutinesTestDispatcherImpl() | | Testing multiple scenarios in one test | Split into separate @Test functions | | Skipping @BeforeTest cleanup | Add setup() calling clean() on every fake | | Constructing ViewModel in @BeforeTest | Construct at field level so it shares dispatcher context | | Omitting Given/When/Then comments | Always add the three comment blocks | | Vague test names like testUpdate() | Rename to describe the scenario and expected outcome |

Related Skills

• ViewModel tests → use write-viewmodel skill for ViewModel construction patterns
• UI behavior tests → use write-ui-tests skill
• Full user flow tests → use write-e2e-tests skill