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.

[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:

   [plugins]
   roborazzi = { id = "io.github.takahirom.roborazzi", version.ref = "roborazzi" }
   

2. Apply it in your module's build.gradle.kts:

   plugins {
       alias(libs.plugins.roborazzi)
   }
   

Writing a Screenshot Test

@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()
    }
}