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Top JUnit Interview Questions for Your Technical Interview

by Interview Kickstart Team in Interview Questions
October 14, 2022

Top JUnit Interview Questions for Your Technical Interview

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JUnit is one of the most popular unit testing frameworks explicitly built for the Java language. It is also one of the most widely used frameworks specifically for regression testing. JUnit is part of a family of unit testing frameworks known collectively as xUnit.

If you are a developer or tester who codes in Java, you’re expected to know answers to common JUnit interview questions at technical rounds of software engineering and testing interviews. To give you an understanding of the type of questions to expect at your upcoming interview, we’ve compiled a list of top JUnit interview questions for experienced java developers and freshers. 

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Let’s go ahead and look at some common JUnit interview questions asked at testing and Java developer interviews. We’ll look at JUnit interview questions for experienced developers and freshers. 

Here’s what we’ll cover in this article:

  • Common JUnit Interview Questions and Answers
  • JUnit Interview Questions for Experienced Professionals
  • FAQs on JUnit Interview Questions

Common JUnit Interview Questions and Answers

Knowing answers to commonly asked JUnit interview questions is important to set yourself apart in Java developer and tester interviews. Here are a few common JUnit interview questions and answers, followed by some sample JUnit interview questions asked specifically at interviews for freshers and junior programmers. 

Q1. What are some prominent advantages of using JUnit?

This is one of the most common JUnit interview questions asked at technical interviews. 

Some prominent advantages of using JUnit include

  • It helps to automate test cases.
  • It allows developers to refactor code.
  • Helps to rectify logic in code when there is a deviation from optimal code
  • Helps to reduce overall testing costs

Q2. What are the core features of JUnit?

This is another common JUnit interview question asked at Java developer and tester interviews. 

Some core features of JUnit include:

  • It allows developers and testers to perform regression testing
  • It provides specific annotations for identifying various test methods
  • It offers a platform that allows test cases to run automatically
  • It allows testers and developers to perform automated testing of test cases

Q3. What is the function of the @Before annotation in JUnit?

The @Before annotation in JUnit executes initialization statements and preconditions before running the particular test case.

Q4. What is the use of the @ignores annotation in JUnit?

This is one of the most common JUnit interview questions asked at technical interviews. @ingores in JUnit ignore specific conditions and initialization statements while executing test cases.

Q5. What do you understand about the @RunWith annotation?

The @RunWith annotation is used to run JUnit test cases with custom JUnit runners such as MockitoJUnitRunner, and SpringJUnit4ClassRunner. It also allows developers and testers to perform parameterized testing on the JUnit test framework.  

Sample JUnit Interview Questions for Your Upcoming Interview

In this section, we’ll look at some sample interview questions in JUnit, mostly asked at interviews for freshers. 

  1. What do you understand about the @after annotation in JUnit?
  2. What do you understand about the @Type annotation in JUnit?
  3. What are Assert methods in JUnit?
  4. What do you understand by a test suite in JUnit?
  5. What do you understand by a JUnit fixture?
  6. What do you understand by Stubbing and Mocking in JUnit?
  7. How do you achieve test isolation in JUnit?
  8. Explain the process of writing a typical test case in JUnit.
  9. What is the @BeforeClass annotation in JUnit?
  10. What is the @AfterClass annotation in JUnit?

JUnit Interview Questions for Experienced Programmers and Testers

As an experienced programmer, your knowledge of JUnit and other unit testing frameworks is evaluated in Java interviews. 

To give you an idea of what to expect, we’ve compiled a list of common JUnit interview questions for experienced developers. 

  1. What are some best practices to follow while writing JUnit test cases?
  2. How would you run the JUnit environment from the command window?
  3. How do you test protected methods in JUnit?
  4. Explain how to assert exceptions thrown in JUnit tests
  5. What do you understand about Hamcrest Matchers in JUnit?
  6. What do you understand by cyclomatic complexity of code?
  7. What are code coverages?
  8. How do you test private methods in JUnit?
  9. Why is mocking required in Unit Testing?
  10. What is the difference between @injectmocks and @mock?
  11. How do you mock void methods in Mockito?
  12. What is the function of SPY in JUnit?

Practicing these JUnit interview questions will help you get interview-ready for your next Java developer/tester interview.

FAQs on JUnit Interview Questions

Q1. Which programming language is JUnit developed explicitly for?

JUnit is a unit testing framework specifically developed for Java. It is part of a family of unit testing frameworks known collectively as xUnit. 

Q2. Where are JUnit interview questions typically asked?

JUnit interview questions are typically asked at Java developer and tester interviews. Questions are typically around the framework’s core features and functionalities.

Q4. What important topics should be prepared to answer JUnit coding interview questions?

JUnit interview questions at technical interviews are typically around JUnit test cases, annotations, methods, unit testing, regression testing, fixtures, and code coverages.

Q5. What is the average Java developer salary in the US?

The average Java developer salary in the United States is $97,343 per year, according to glassdoor.com

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How you can accelerate your learnings
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