# Android Testing (Android)

> JUnit, Espresso, unit tests, instrumented tests, assertions

- 28 interview questions
- Junior
- [Interview Questions: Android](https://sharpskill.dev/en/technologies/android/interview-questions.md)

## 1. What is JUnit?

**Answer**

JUnit is a unit testing framework for Java and Kotlin. It's the standard for writing and executing automated tests. JUnit 4 uses annotations (@Test, @Before, @After) to define tests and their lifecycle. JUnit tests are fast because they run on the local JVM without Android emulator.

## 2. What is the @Test annotation used for?

**Answer**

@Test marks a method as a unit test. The method will be executed by the test runner. Without @Test, the method is ignored. Example: @Test fun testAddition() { assertEquals(4, 2 + 2) }. Each @Test must be independent and not depend on execution order.

## 3. What is the @Before annotation used for?

**Answer**

@Before marks a method that executes BEFORE each test (@Test). Useful for initializing common objects, creating mocks, resetting state. Example: @Before fun setUp() { viewModel = MyViewModel() }. If you have 5 tests, @Before runs 5 times. Alternative: @BeforeClass for single execution before all tests.

## 25 more questions available

- What is the @After annotation used for?
- What is an assertion in testing?

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## Other Android interview topics

- [Android Fundamentals](https://sharpskill.dev/en/technologies/android/interview-questions/android-fundamentals.md): 24 questions, Junior
- [Android UI and Resources](https://sharpskill.dev/en/technologies/android/interview-questions/android-ui-and-resources.md): 30 questions, Junior
- [Android Lifecycle](https://sharpskill.dev/en/technologies/android/interview-questions/android-lifecycle.md): 30 questions, Junior
- [Android Navigation](https://sharpskill.dev/en/technologies/android/interview-questions/android-navigation.md): 26 questions, Junior
- [Android Data Management](https://sharpskill.dev/en/technologies/android/interview-questions/android-data-management.md): 29 questions, Junior
- [Android Networking](https://sharpskill.dev/en/technologies/android/interview-questions/android-networking.md): 29 questions, Junior
- [Android Gradle](https://sharpskill.dev/en/technologies/android/interview-questions/android-gradle.md): 26 questions, Junior
- [Kotlin Language Essentials for Android](https://sharpskill.dev/en/technologies/android/interview-questions/android-kotlin-language-essentials.md): 24 questions, Junior
- [Room Database](https://sharpskill.dev/en/technologies/android/interview-questions/android-room-database.md): 25 questions, Mid-Level
- [Background Work](https://sharpskill.dev/en/technologies/android/interview-questions/android-background-work.md): 18 questions, Mid-Level
- [Jetpack Compose](https://sharpskill.dev/en/technologies/android/interview-questions/android-compose.md): 28 questions, Mid-Level
- [Permissions and Device Features](https://sharpskill.dev/en/technologies/android/interview-questions/android-permissions-and-device.md): 21 questions, Mid-Level
- [Firebase for Android](https://sharpskill.dev/en/technologies/android/interview-questions/android-firebase.md): 23 questions, Mid-Level
- [Android MVVM Architecture](https://sharpskill.dev/en/technologies/android/interview-questions/android-mvvm-architecture.md): 18 questions, Mid-Level
- [Advanced Android Networking](https://sharpskill.dev/en/technologies/android/interview-questions/android-networking-advanced.md): 13 questions, Mid-Level
- [Kotlin Collections and Operators](https://sharpskill.dev/en/technologies/android/interview-questions/android-kotlin-collections-operators.md): 20 questions, Mid-Level
- [Kotlin Coroutines and Flow](https://sharpskill.dev/en/technologies/android/interview-questions/android-kotlin-coroutines-flow.md): 20 questions, Mid-Level
- [Android Dependency Injection](https://sharpskill.dev/en/technologies/android/interview-questions/android-dependency-injection.md): 15 questions, Mid-Level
- [Android MVI Architecture](https://sharpskill.dev/en/technologies/android/interview-questions/android-mvi-architecture.md): 17 questions, Mid-Level
- [Android Clean Architecture](https://sharpskill.dev/en/technologies/android/interview-questions/android-clean-architecture.md): 21 questions, Senior
- [Android Compose Advanced](https://sharpskill.dev/en/technologies/android/interview-questions/android-compose-advanced.md): 17 questions, Senior
- [Android Performance and Monitoring](https://sharpskill.dev/en/technologies/android/interview-questions/android-performance-monitoring.md): 13 questions, Senior
- [Android Security and Privacy](https://sharpskill.dev/en/technologies/android/interview-questions/android-security-privacy.md): 18 questions, Senior
- [Android CI/CD and Release](https://sharpskill.dev/en/technologies/android/interview-questions/android-cicd-release.md): 15 questions, Senior
- [Android UX and Form Factors](https://sharpskill.dev/en/technologies/android/interview-questions/android-ux-form-factors.md): 18 questions, Senior
- [Android Testing Advanced](https://sharpskill.dev/en/technologies/android/interview-questions/android-testing-advanced.md): 18 questions, Senior

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