Espresso

Espresso (Mobile UI Automation Demo)

Project map

Do not run builds or tests yourself — ask the user to run ./scripts/run-android.sh after changes.

For iOS parity, use the xctest skill.

Conventions

1. Selectors — Use @+id/... in layouts; query with withId(R.id....) in tests.
2. No sleeps — Espresso syncs with the main thread; register CountingIdlingResource for coroutines/network.
3. Test source set — Instrumented UI tests live in androidTest, not test (unit).
4. Runner — AndroidJUnitRunner (see android/app/build.gradle.kts).
5. Package — com.example.mobileuiautomationdemo.

View IDs (home + weather)

Add in layout XML:

<Button
    android:id="@+id/get_weather_button"
    ... />

Adding a test

Task progress:
- [ ] Add @+id in layout if missing
- [ ] Add *EspressoTest.kt in androidTest/
- [ ] Mirror scenario in XCUITest (see xctest skill) for shared flows
- [ ] Update test-data/ if assertions use shared JSON
- [ ] Ask user to run ./scripts/run-android.sh

Static screen (smoke)

@RunWith(AndroidJUnit4::class)
class MainActivityEspressoTest {

    @get:Rule
    val activityRule = ActivityScenarioRule(MainActivity::class.java)

    @Test
    fun homeScreen_showsWelcomeAndProductDetails() {
        onView(withId(R.id.welcome_title))
            .check(matches(isDisplayed()))
            .check(matches(withText("Welcome to Mobile UI Demo")))

        onView(withId(R.id.product_name))
            .check(matches(withText("Example Product")))
    }
}

Prefer withId over withText alone when an id exists.

Async / network (weather pattern)

Open-Meteo HTTPS — needs network; may fail offline in CI. Note in PRs when adding similar tests.

Expose idling resource from the activity; register in test try/finally:

activityRule.scenario.onActivity { activity ->
    IdlingRegistry.getInstance()
        .register(activity.getWeatherRequestIdlingResource())
}
try {
    onView(withId(R.id.get_weather_button)).perform(click())

    onView(withId(R.id.weather_result))
        .check(matches(isDisplayed()))
        .check(matches(withText(containsString("San Francisco"))))
        .check(matches(withText(matchesRegex(".*\\d+(\\.\\d+)?°F"))))
} finally {
    activityRule.scenario.onActivity { activity ->
        IdlingRegistry.getInstance()
            .unregister(activity.getWeatherRequestIdlingResource())
    }
}

Activity pattern — increment() before async work, decrement() in finally:

private val weatherRequestIdlingResource = CountingIdlingResource("weather_request")

weatherRequestIdlingResource.increment()
lifecycleScope.launch {
    try { /* work */ } finally { weatherRequestIdlingResource.decrement() }
}

Never Thread.sleep.

Dependencies

From android/app/build.gradle.kts:

• androidx.test.espresso:espresso-core:3.7.0
• androidx.test.espresso:espresso-idling-resource:3.7.0
• androidx.test.ext:junit, androidx.test:runner, androidx.test:rules

Naming

• Class: FeatureEspressoTest
• Methods: feature_expectedOutcome (snake_case)

Anti-patterns

• Thread.sleep / fixed delays
• withText when @+id is available
• UI tests in src/test instead of src/androidTest
• Network tests in CI without documenting connectivity requirement
• Forgetting to unregister idling resources in finally

Further reading

• reference.md — matchers, idling checklist, troubleshooting
• docs/test-strategy.md
• docs/android-setup.md
• docs/troubleshooting.md