E2E Testing Demo — Android Jetpack Compose

A practical reference project for writing reliable, maintainable end-to-end tests for Android apps built with Jetpack Compose.

Companion source code for the article: "E2E Testing for Android with Jetpack Compose: A Practical Guide"

---

What This Project Demonstrates

• End-to-end testing of a full login flow using the Compose testing API
• Page Object Model (POM) for readable, maintainable test code
• MockWebServer for deterministic network stubbing — no real API calls in tests
• Custom JUnit rules for mock server lifecycle and on-failure screenshots
• CI/CD pipeline with GitHub Actions running tests on an Android emulator

---

Tech Stack

Layer	Technology
Language	Kotlin
UI	Jetpack Compose + Material 3
Navigation	Navigation Compose
Architecture	MVVM (ViewModel + StateFlow)
Testing	Compose UI Test, AndroidJUnit4, UiAutomator
Network mocking	OkHttp MockWebServer
CI	GitHub Actions

SDK targets: minSdk = 30, targetSdk = 36, compileSdk = 36

---

Project Structure

app/src/
├── main/
│   └── java/com/example/e2etestdemo/
│       ├── MainActivity.kt
│       ├── navigation/
│       │   └── AppNavigation.kt          # NavHost with login → home routes
│       ├── data/
│       │   ├── AuthRepository.kt         # Interface
│       │   ├── DefaultAuthRepository.kt  # HTTP implementation (dummyjson.com)
│       │   └── RepositoryProvider.kt     # Global singleton for DI in tests
│       └── ui/
│           ├── TestTags.kt               # Centralized semantic tags
│           ├── login/
│           │   ├── LoginScreen.kt
│           │   ├── LoginViewModel.kt
│           │   └── LoginUiState.kt
│           └── home/
│               └── HomeScreen.kt
│
└── androidTest/
    └── java/com/example/e2etestdemo/
        ├── LoginFlowTest.kt              # E2E test suite (5 test cases)
        ├── pages/
        │   ├── LoginPage.kt              # Page Object for LoginScreen
        │   └── HomePage.kt              # Page Object for HomeScreen
        ├── rules/
        │   ├── MockServerRule.kt         # Starts/stops MockWebServer per test
        │   └── ScreenshotRule.kt         # Captures screenshot on failure
        └── utils/
            ├── MockResponses.kt          # Canned HTTP responses
            └── ComposeTestExtensions.kt  # waitUntilExists helper

---

Test Cases

ID	Test	Scenario
TC-001	successfulLogin_navigatesToHomeWithUsername	Valid credentials → navigates to Home
TC-002	emptyUsername_showsValidationError	Empty username → client-side error
TC-003	emptyPassword_showsValidationError	Empty password → client-side error
TC-004	wrongCredentials_showsServerErrorMessage	Server returns 401 → "Invalid credentials"
TC-005	networkFailure_showsGenericError	Server closes connection → network error message

---

Key Patterns

Page Object Model

Tests read as user stories, not UI queries:

loginPage
    .enterUsername("emilys")
    .enterPassword("emilyspass")
    .clickLogin()

homePage.assertWelcomeMessage("emilys")

MockWebServer Rule

Network is fully controlled — no flakiness from real APIs:

@get:Rule(order = 0) val mockServer = MockServerRule()

mockServer.server.enqueue(MockResponses.loginSuccess("emilys"))

Rule Ordering

MockServerRule(0)  → server starts, RepositoryProvider wired to localhost
ComposeRule(1)     → Activity launches, reads RepositoryProvider
ScreenshotRule(2)  → wraps test; captures screenshot on failure

---

Running the Tests

Locally

# Run all E2E tests on a connected device or emulator
./gradlew connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.size=large

Test reports are saved to:

app/build/reports/androidTests/connected/

Failure screenshots are saved to the device at:

/sdcard/Android/data/com.example.e2etestdemo/files/screenshots/

Pull them with:

adb pull /sdcard/Android/data/com.example.e2etestdemo/files/screenshots/

CI (GitHub Actions)

Tests run automatically on every push and pull request to main via .github/workflows/android-e2e.yml.

• Emulator: API 34, Pixel 6 profile, x86_64
• Artifacts uploaded on every run: test reports
• Artifacts uploaded on failure: failure screenshots

---

License

MIT