android-instrumented-testing

Android Instrumented Testing

On device/emulator run only what the JVM doesn't prove: Compose/Espresso, navigation, intents, permissions. ViewModel unit: android-unit-testing.

Stack and scope

Item	Role
androidTest	Instrumented source set
Compose Test	`createAndroidComposeRule` / semantics
Espresso	Legacy XML Views
HiltAndroidRule	Test DI if the app uses Hilt
UI Automator	Only cross-app / system

Don't instrument a pure use case. Prefer test/ until it hurts.

What to prioritize

Happy path of critical screen (login, checkout, permission)
Visible empty/error states
Navigation (back stack)
Basic accessibility (contentDescription on targets)
UI bug regression

Layout

src/androidTest/kotlin/.../
  fakes/
  screens/          # robots ou page objects
  FooScreenTest.kt

One class per flow. Robots reduce coupling to semantics.
testInstrumentationRunner of the project (Hilt runner if Hilt).

Compose Test

composeRule.setContent { AppTheme { Screen(state, onEvent) } }
composeRule.onNodeWithTag("submit").performClick()
composeRule.onNodeWithText("Salvo").assertIsDisplayed()

Semantics: testTag stable on test targets; not just fragile i18n text.
waitUntil / waitForIdle — without Thread.sleep.
Inject fake ViewModel or repo fakes via factory/Hilt test module.
Idle: coroutines — IdlingResource only if the project already has it; Compose waits for recomposition.

Espresso (XML)

onView(withId(...)).perform(click()). Idling for OkHttp if already configured.
Don't mix Espresso and Compose in the same method without the project's bridge.

Isolation

Build flavor / debug test only. No real staging.
Permissions: grant in GrantPermissionRule or CI ADB.
Reset DataStore/Room between tests (in-memory test DB or clear).
Disable animations in the CI runner (ANIMATOR_DURATION_SCALE=0).

Flakiness

Common cause: async without idle, animations, time/network.
Retry on CI only with evidence; prefer fixing idle.
Avoid Thread.sleep.
Screenshots on failure on CI if the pipeline already supports it.

Anti-patterns

Instrumenting 100% of screens
Assert by coordinate/pixel
Real network in PR
testTag on all nodes “just in case”
Duplicating ViewModel tests that already pass on the JVM

Integration with other skills

Unit: android-unit-testing
Compose: jetpack-compose
App: android-development
Coroutines in fakes: kotlin-coroutines

Completion criteria

Critical flow covered without sleep
Fakes/Hilt test; no shared backend
Stable semantics
Suite connectedDebugAndroidTest (or the CI flavor) green in scope