android-testing

# Android Testing Strategies This skill provides expert guidance on testing modern Android applications, inspired by "Now in Android". It covers **Unit Tests**, **Hilt Integration Tests**, and **Screenshot Testing**. ## Testing Pyramid 1. **Unit Tests**: Fast, isolate logic (ViewModels, Repositories). 2. **Integration Tests**: Test interactions (Room DAOs, Retrofit vs MockWebServer). 3. **UI/Screenshot Tests**: Verify UI correctness (Compose). ## Dependencies (`libs.versions.toml`) Ensure you have the right testing dependencies. ```toml [libraries] junit4 = { module = "junit:junit", version = "4.13.2" } kotlinx-coroutines-test = { group = "org.jetbrains.kotlinx", name = "kotlinx-coroutines-test", version.ref = "kotlinxCoroutines" } androidx-test-ext-junit = { group = "androidx.test.ext", name = "junit", version = "1.1.5" } espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version = "3.5.1" } compose-ui-test = { group = "androidx.compose.ui", name = "ui-test-junit4" } hilt-android-testing = { group = "com.google.dagger", name = "hilt-android-testing", version.ref = "hilt" } roborazzi = { group = "io.github.takahirom.roborazzi", name = "roborazzi", version.ref = "roborazzi" } ``` ## Screenshot Testing with Roborazzi Screenshot tests ensure your UI doesn't regress visually. NiA uses **Roborazzi** because it runs on the JVM (fast) without needing an emulator. ### Setup 1. Add the plugin to `libs.versions.toml`: ```toml [plugins] roborazzi = { id = "io.github.takahirom.roborazzi", version.ref = "roborazzi" } ``` 2. Apply it in your module's `build.gradle.kts`: ```kotlin plugins { alias(libs.plugins.roborazzi) } ``` ### Writing a Screenshot Test ```kotlin @RunWith(AndroidJUnit4::class) @GraphicsMode(GraphicsMode.Mode.NATIVE) @Config(sdk = [33], qualifiers = RobolectricDeviceQualifiers.Pixel5) class MyScreenScreenshotTest { @get:Rule val composeTestRule = createAndroidComposeRule<ComponentActivity>() @Test fun captureMyScreen() { composeTestRule.setContent { MyTheme { MyScreen() } } composeTestRule.onRoot() .captureRoboImage() } } ``` ## Hilt Testing Use `HiltAndroidRule` to inject dependencies in tests. ```kotlin @HiltAndroidTest class MyDaoTest { @get:Rule var hiltRule = HiltAndroidRule(this) @Inject lateinit var database: MyDatabase private lateinit var dao: MyDao @Before fun init() { hiltRule.inject() dao = database.myDao() } // ... tests } ``` ## Running Tests * **Unit**: `./gradlew test` * **Screenshots**: `./gradlew recordRoborazziDebug` (to record) / `./gradlew verifyRoborazziDebug` (to verify)