Test (Android Test Pyramid Compliant)

Create tests based on the official Android testing guidelines.

Test Pyramid

        /  E2E  \          Few: Complete user flows
       /----------\
      / Integration \      Moderate: Multi-unit interactions
     /----------------\
    /    Unit Tests     \  Many: Individual class verification
   /____________________\

Test Types and Strategy

Unit Tests (Highest Priority)

Target: ViewModel, UseCase, Repository, Utility classes Location: app/src/test/ Framework: JUnit 4/5 + kotlinx-coroutines-test

ViewModel Test Example

class XxxViewModelTest {
    @get:Rule
    val mainDispatcherRule = MainDispatcherRule()

    private lateinit var viewModel: XxxViewModel
    private lateinit var fakeRepository: FakeXxxRepository

    @Before
    fun setup() {
        fakeRepository = FakeXxxRepository()
        viewModel = XxxViewModel(fakeRepository)
    }

    @Test
    fun `initial state is correct`() = runTest {
        val state = viewModel.uiState.value
        assertEquals(XxxUiState(), state)
    }

    @Test
    fun `action updates state correctly`() = runTest {
        viewModel.onAction(XxxAction.DoSomething)
        val state = viewModel.uiState.value
        assertTrue(state.isLoading)
    }
}

Testing Rules

• •Fake > Mock: Prefer Fake implementations over mocking libraries (Google's official recommendation)
• •1 test = 1 assertion: Each test verifies a single behavior
• •Naming: Use backtick syntax `descriptive test name`()
• •AAA Pattern: Arrange → Act → Assert
• •Coroutine testing: Use runTest + TestDispatcher
• •Edge cases: Test error paths and boundary conditions, not just the happy path

Integration Tests

Target: Repository + DataSource interaction, multi-UseCase coordination Location: app/src/test/ or app/src/androidTest/

UI Tests (Compose)

Target: Screen display and interaction Location: app/src/androidTest/ Framework: Compose Testing (createComposeRule)

class XxxScreenTest {
    @get:Rule
    val composeTestRule = createComposeRule()

    @Test
    fun displaysCorrectContent() {
        composeTestRule.setContent {
            XxxScreen(state = XxxUiState(title = "Hello"))
        }
        composeTestRule.onNodeWithText("Hello").assertIsDisplayed()
    }
}

Test Creation Procedure

Step 1: Analyze the Target

• •Read the class/feature to be tested
• •Identify dependencies
• •List behaviors to test

Step 2: Prepare Test Doubles

• •Repository → Create FakeXxxRepository
• •DataSource → Create FakeXxxDataSource
• •Dispatcher → Use TestDispatcher
• •Create MainDispatcherRule (if not existing)

Step 3: Implement Tests

• •Happy path tests
• •Error path tests
• •Boundary value tests
• •State transition tests (for ViewModels)

Step 4: Run and Verify

./gradlew test                      # Unit tests
./gradlew connectedAndroidTest      # Instrumentation tests

Target

If $ARGUMENTS is specified, create tests for that class/feature. If not specified, identify areas with insufficient test coverage and add tests in priority order.