20 Android Unit Testing Interview Questions and Answers

Android Unit Testing is a process of testing the functionality of individual units of code in an Android app. This process helps ensure that the app is functioning properly and can help identify any potential bugs. When interviewing for an Android development position, you may be asked questions about your unit testing process and how you would go about testing various aspects of the app. In this article, we review some common Android Unit Testing interview questions and provide example answers to help you prepare for your next interview.

Android Unit Testing Interview Questions and Answers

Here are 20 commonly asked Android Unit Testing interview questions and answers to prepare you for your interview:

1. What are unit tests in the context of Android?

Unit tests are tests that focus on a single component or small group of components in an Android app. These tests help to ensure that the code for these components is working as expected. Android unit tests are typically written in Java.

2. Why is it important to write unit tests for an Android application?

Unit tests help to ensure that the individual components of an Android application are functioning correctly. By writing unit tests, developers can catch bugs early on and prevent them from becoming bigger issues later on. Additionally, unit tests can help to improve the overall quality of an Android application by helping to ensure that all of its components are working correctly.

3. Can you explain how a typical test case works in Android?

A typical test case in Android will test a specific functionality in an Android app. For example, a test case might test the login functionality of an app. To do this, the test case would need to provide input values for a username and password, and then check to see if the app correctly logs the user in.

4. How does dependency injection work on Android? Can you give me some examples?

Dependency injection is a technique used to remove dependencies between different parts of code. In the context of Android, this means that you can inject objects into an Activity or Fragment without having to create those objects in the activity or fragment itself. This can be done using a number of different frameworks, but the most popular one for Android is Dagger.

5. What’s the difference between Mockito and Robolectric?

Mockito is a library that allows you to create mock objects for testing. Robolectric is a library that allows you to run Android unit tests on a JVM instead of on a device or emulator.

6. What are some common tools used for unit testing in Android?

There are a few different tools that can be used for unit testing in Android, but some of the most popular ones include JUnit, Robolectric, and Espresso. Each of these tools has its own strengths and weaknesses, so it’s important to choose the one that’s right for your particular project.

7. What is Espresso?

Espresso is a testing tool for Android that allows you to test the functionality of your app from within the Android Studio IDE. With Espresso, you can write tests that simulate user interactions and verify that the results are as expected.

8. What is JUnit? Why do we use it in Android development?

JUnit is a unit testing framework for Java that helps developers test individual pieces of code to ensure that they are functioning as intended. In Android development, JUnit is used to test the functionality of Android applications before they are released to the public. By using JUnit, developers can catch bugs and errors early on, which makes for a better overall user experience.

9. Can you explain what a mock object is in Android development?

A mock object is a test object that simulates the behavior of a real object. In Android development, mock objects can be used to simulate the behavior of a real Android object, such as an Activity or a Fragment. This allows you to test the behavior of your code without having to actually launch the Android object.

10. Is it possible to create a sample app using only unit tests? If yes, then please show me how.

Yes, it is possible to create a sample app using only unit tests. However, it is generally not considered a good practice to do so, as it can lead to a lot of duplication of code and can make the code more difficult to maintain. A better approach would be to create a separate unit test project that contains all of the unit tests for the app, and to only include the code for the app itself in the main project.

11. How can you change the behavior of your code when running unit tests?

You can use the @Test annotation to specify how your code should behave when running unit tests. By default, the @Test annotation will cause your code to run as if it were being executed in a production environment. However, you can use the @Test annotation to specify that your code should behave differently when running unit tests. For example, you can use the @Test annotation to specify that your code should run in a mock environment. This can be useful for testing code that interacts with external services.

12. When would you want to run unit tests against an emulator or device instead of an AVD?

You would want to run unit tests against an emulator or device instead of an AVD if you are testing features that are specific to the hardware of the device, such as the camera or GPS.

13. What is coverage and why is it so important to achieve high coverage with unit tests?

Coverage is a measure of how much of your code is being executed by your unit tests. It is important to achieve high coverage because it means that your tests are exercising a large portion of your code, and therefore are more likely to find bugs. It also means that your tests are more likely to be effective in preventing regressions.

14. What are the advantages of writing Unit Tests in Android over other platforms like iOS or Windows Phone?

One of the main advantages of writing Unit Tests in Android is that the Android SDK provides a very comprehensive testing framework that can be used to test almost any aspect of an Android app. This includes testing the UI, database interactions, and even specific hardware features. Additionally, the Android emulator is very fast and easy to use, making it ideal for Unit Testing.

15. How do you organize your unit test cases in Android?

There are a few different ways to organize your unit test cases in Android. One way is to create a separate test case for each class that you want to test. Another way is to create a test case for each individual method that you want to test.

16. What’s the best way to implement TDD (Test Driven Development) in Android?

There is no one-size-fits-all answer to this question, as the best way to implement TDD in Android will vary depending on the specific project and team. However, some tips on how to implement TDD in Android effectively include:

– Planning and designing tests before writing any code
– Writing tests that are small and focused
– Automating as much of the testing process as possible
– Using a continuous integration server to run tests automatically
– Regularly reviewing and refactoring tests

17. What are some limitations of unit testing in Android?

One of the main limitations of unit testing in Android is the lack of a true emulator environment. This means that unit tests can only be run on actual devices, which can be time-consuming and expensive. Additionally, the Android platform is constantly changing, which can make it difficult to keep unit tests up-to-date.

18. What are some best practices that you follow when writing unit tests in Android?

Some best practices that I follow when writing unit tests in Android are to keep my tests short and focused, to write tests for all public methods in my classes, and to make sure that my tests cover all possible scenarios. Additionally, I always run my tests on a simulator or emulator before running them on a real device to ensure that they will work as expected.

19. What is ActivityInstrumentationTestCase2?

ActivityInstrumentationTestCase2 is a class that provides functional testing of a single activity. You can use this class to test a single activity in isolation from the rest of the system.

20. What is AndroidTestCase?

AndroidTestCase is a class that provides a framework for testing Android applications. It is a subclass of junit.framework.TestCase, and provides functionality to set up and tear down an Android test environment, as well as access to various Android system services.