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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
- Unit Tests: Fast, isolate logic (ViewModels, Repositories).
- Integration Tests: Test interactions (Room DAOs, Retrofit vs MockWebServer).
- 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
- Add the plugin to
libs.versions.toml:
toml
[plugins]
roborazzi = { id = "io.github.takahirom.roborazzi", version.ref = "roborazzi" }- 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)
