JUnit Interview Questions

Q.Explain who should use JUnit – a developer or tester? Why you use JUnit to test your code?

Ans- JUnit is more often used by developers to implement unit tests in JAVA. It is designed for unit  testing that is more a coding process and not a testing process. However, many testers and QA engineers use JUnit for unit testing. JUnit is used because

  It test early and does automate testing.

JUnit tests can be compiled with the build so that at unit level, regression testing can be done. It allows test code re-usage.

  JUnit tests behave as a document for the unit tests when there is a transfer.

Q.Describe the process which is helpful in the creation of parameterized Tests

Ans- In order to answer this question, you need to take into account that there are five steps. These steps are as follows:

1. The first step is that you have to create a public constructor which would take into account the equivalent value of a row of test related data

   2. In the second step, you have to annotate the test class with a command by the name of @Run With

3. In the third step, you have to create a public static procedure which has the ability to return a collection of test data sets

   4. In the fourth step, you need to create a viable which is instantaneous and is the source of data

5. In the last level, you have to make sure that test case is invoked only once per each row. This would facilitate the smooth running of an application.

Q.What is a test fixture with respect to JUnit?

Ans- A test fixture is also known as a regulated state of objects that can be used as a platform for running the tests. The primary purpose is to make sure that there is a known climate in which the development tests can be run. Various examples can be cited in this context. They are as follows:

   1. Copying the fixed known set of files

   2. Preparing the input data and the creation of mock and fake objects

   3. Assessing a database with fixed and known sets of data

It is also essential for you to note that if a group of tests shares the same fittings, one needs to write a different setup code. On the other hand, if the group of assessments is in need of a different test fixture, one can write the code alongside the test procedure. In this manner, one can create the best accessory related to a test.

Q.What is mocking and stubbing? Did you use any mocking framework?

Ans- Mocking is a feature where an object mimics like a real object. Stubbing are codes that are responsible for taking place of another component.

  There are various different Java mocking framework such as Mockito, EasyMock etc.

Q. What is unit testing method-naming convention that you follow?

Ans- The convention you follow should have every information required by the method name in a structured manner. Unit tests name should act like the documentation giving a clear idea of what functionality is tested. There are various techniques that could be used to name unit tests. Some of them are the following: Given… When… Then… Should… etc.

Q. What do following JUnit test annotations mean?

Ans- Use of annotations reduces coding and extra burden from the tester. Following is a list of frequently used JUnit 4 annotations: @Test (@Test identifies a test method)

 @Before (Ans: @Before method will execute before every JUnit4 test)@After (Ans: @After         method will execute after every JUnit4 test)@BeforeClass (Ans: @BeforeClass method will be   executed before the JUnit test for a Class starts)@AfterClass (@AfterClass method will be   executed after the JUnit test for a Class is completed)@Ignore (@Ignore method will not be       executed

Q.What are the important JUnit annotations?

  Ans- The test runner is used to execute the test cases.

  @Test: This is the test method to run first unless otherwise specified.

@BeforeClass: This is run once before any of the other test methods present in the class. @Before: This is run before @Test.

  @After: As the name suggests, this is run after the @Test.

  @AfterClass: This is run one after all of the tests in the class have been run.

Q.What are the useful JUnit extensions? 

Ans-There are several JUnit extensions such as:

JWebUnit XMLUnit Cactus MockObject

Q.Explain how you can write a simple JUnit test case? 

Ans- The simplest way to write a JUnit test case is:

   Determine a subclass of TestCase

To initialize object(s) under test, override the setup() method To release object(s) under test override the teardown() method

Determine one or more public test XYZ() methods that exercise the objects under test and assert expected results.

Q.Explain what is meant by ignoring test in JUnit?

Ans- When your code is not ready, and it would fail if executed then you can use @Ignore annotation. It will not execute a test method annotated with @Ignore

   It will not execute any of the test methods of test class if it is annotated with @Ignore

Q.How is code cyclomatic complexity related to unit tests?

Ans- As code cyclomatic complexity is determined based on number of decision points within the code and hence execution paths, higher cyclomatic complexity makes it difficult to attain achieve test/code coverage

Q.When are the unit tests pertaining to JUnit written in Developmental Cycle?

Ans- The unit tests are written before the development of the application. It is so because by writing the check before coding, it assists the coders to write error-free codes which further boosts the viability of the form.