Interview Questions.

JUnit Interview Questions and Answers - Jul 16, 2022


JUnit Interview Questions and Answers

Q1. What is JUnit?

Ans: JUnit is a testing framework for unit testing.  It uses Java as a programming platform, and it is an Open Source Software controlled by using the JUnit.Org community.

Q2. What is Unit Test Case?

Ans: Unit Test Case is a part of the code that guarantees that the any other part of code (approach) behaves as anticipated. For each requirement, there ought to be at least two check cases one bad check and one fantastic take a look at.

Q3. List vital capabilities of JUnit?

Ans: The important capabilities of JUnit:

It is an open source framework.

Provides Annotation to identify the check techniques.

Provides Assertions for testing expected results.

Provides Test runners for going for walks checks.

JUnit tests can be run mechanically and that they take a look at their personal outcomes and offer on the spot comments.

JUnit checks can be organized into check suites containing test instances and even different check suites.

JUnit indicates take a look at progress in a bar this is inexperienced if check goes exceptional and it turns crimson whilst a check fails.

Q4. How to install JUnit?

Ans: Installation steps for JUnit :

Download the modern-day model of JUnit, cited beneath as junit.Zip.

Unzip the junit.Zip distribution report to a listing known as %JUNIT_HOME%.

Add JUnit to the classpath −


Test the set up by means of running the sample checks allotted with JUnit (sample exams are located in the installation directory without delay, now not the junit.Jar document). Then truly kind −

java org.Junit.Runner.JUnitCore org.Junit.Tests.AllTests

All the checks ought to pass with an "OK" message. If the tests do not pass, confirm that junit.Jar is within the CLASSPATH.

Q5.  How you may write a simple JUnit check case?


Determine a subclass of TestCase

To initialize object(s) below take a look at, override the setup() technique

To launch item(s) beneath check override the teardown() method

Determine one or greater public take a look at XYZ() techniques that exercise the objects below check and assert predicted results.

Q6. What are parameterized assessments?

Ans: Parameterized checks allow developer to perform the equal take a look at over and again using unique values.

Q7. What is the difference between JUnit and TestNG?


                                JUnit                                       TestNG

In JUnit the naming conference for annotation is a bit complex for, e.G., “Before”, “After” and “Expected”

In JUnit, for a technique assertion you have to comply with a selected style like using “@BeforeClass” and “@AfterClass”.

In JUnit approach name constraint is gift

JUnit framework does not have “Parameterized Test” or “Dependency Test” function

In JUnit grouping of check cases are not available

JUnit does not aid parallel execution on Selenium take a look at instances

It cannot re-run the failed cases

 In TestNG it's miles less complicated to understand annotations like “BeforMethod”, “AfterMethod” and “ExpectedException”

In TestNG, there's no limit like you need to declare methods in a specific format

In TestNG approach call constraint isn't always present, and you may decide any check method names

TestNG use “dependOnMethods” to enforce the dependency checking out

In TestNG, grouping of test instances is to be had

In TestNG Parallel execution of Selenium test instances are viable

It can rerun the failed exams

Q8. What are the one-of-a-kind methods of exception coping with in JUnit?

Ans: Different methods of exception coping with in JUnit are:

Try capture idiom

With JUnit rule

With @Test annotation

With catch exception library

With customs annotation


Q9. How do I take a look at matters that must be run in a J2EE container (e.G. Servlets, EJBs)?


Ans: Refactoring J2EE components to delegate capability to different items that don't ought to be run in a J2EE container will improve the design and testability of the software. Cactus is an open supply JUnit extension that may be used for unit trying out server-side java code.

Q10.  What is forget about check in JUnit?

Ans: When your code isn't always prepared, and it might fail if accomplished then you may use @Ignore annotation.

It will now not execute a check approach annotated with @Ignore

It will now not execute any of the take a look at methods of test class if it is annotated with @Ignore

Q11.  Mention  some useful JUnit extensions?

Ans: JUnit extensions consist of:





Q12. Explain who must use JUnit – a developer or tester? Why you use JUnit to test your code?

Ans: JUnit is greater regularly used by builders to put in force unit checks in JAVA.  It is designed for unit testing that is extra a coding manner and no longer a trying out manner. However, many testers and QA engineers use JUnit for unit trying out.

JUnit is used because:

It check early and does automate checking out

JUnit tests can be compiled with the build so that at unit level, regression trying out may be accomplished

It lets in take a look at code re-usage

JUnit exams behave as a record for the unit assessments whilst there may be a transfer

Q13. What is JUnitCore Class?

Ans: JUnitCore magnificence is an built in elegance in JUnit package deal; it's miles primarily based on Façade design sample, this magnificence is used to run best specific take a look at lessons simplest.

Q14. Explain the execution manner of the JUint take a look at API strategies?


Ans: Following is how the JUnit execution system works:

First of all technique annotated as @BeforeClass execute simplest once.

Lastly, the method annotated as @AfterClass executes best once.

Method annotated as @Before executes for every test case however earlier than executing the test case.

Method annotated as @After executes for every take a look at case but after the execution of test case.

In between approach annotated as @Before and approach annotated as @After every take a look at case executes.

Q15.   How you can run JUnit from the command window?

Ans: To run JUnit from the command window, you have to comply with the stairs:


Invoke the runner

Q16. What are JUnit Classes? List a number of them.

Ans: JUnit instructions are vital instructions that are used in writing and testing JUnits. Some of the crucial lessons are:

Assert: It contains a set of assert techniques.

TestCase: It carries a take a look at case defines the fixture to run multiple checks.

TestResult: It carries techniques to accumulate the effects of executing a take a look at case.

TestSuite: It is a Composite of Tests.

Q16. What are annotations and the way are they useful in JUnit?

Ans: Annotations are like meta-tags that you could upload to you code and practice them to strategies or in elegance. The annotation in JUnit gives us facts approximately check techniques, which strategies are going to run earlier than & after check methods, which strategies run earlier than & after all of the methods, which techniques or magnificence could be ignore for the duration of execution.

Q17. How will you run JUnit from command window?

Ans: Follow the steps below:


Invoke the runner

java org.Junit.Runner.JUnitCore

Q18. What are the dangers of guide trying out?

The disadvantages of manual checking out are as follows:

Time ingesting: As check instances are finished with the aid of human assets so it is very gradual and tedious.

Huge funding in human sources: As take a look at instances want to be carried out manually so greater analyzers are required in manual testing.

Less dependable: It is much less reliable as checks may not be done with exactness whenever because of human mistakes.

Non-programmable: No programming may be carried out to write complex checks which get concealed facts.

Q19. What are the advantages of automated testing?


The advantages of computerized trying out are as follows:

Fast: Automation checking out technique is significantly quicker than human sources.

Less investment in human sources: Test cases are done by way of using automation device so much less tester are required in automation trying out.

More reliable: Automation exams put into effect exactly identical operation each time they're run.

Programmable: Testers can software sophisticated checks to get the hidden data.

Q20. Name the equipment with which JUnit can be without difficulty included.

Ans: JUnit Framework can be easily integrated with either of the followings:




Q21. What is a fixture?

Ans: Fixture is a set nation of a fixed of objects used as a baseline for walking assessments. The purpose of a test fixture is to make certain that there is a famous and glued environment in which tests are run so that consequences are repeatable. It includes following methods:

setUp() technique which runs before every check invocation.

TearDown() approach which runs after each test technique.

Q22. What is a test suite?

Ans: Test suite way package deal a few unit take a look at cases and run it together. In JUnit, both @RunWith and @Suite annotation are used to run the suite take a look at.

Q23. What is a test runner?

Ans: Test runner is used for executing the test cases.

Q24. What is the reason of org.Junit.TestResult elegance?

Ans: A TestResult collects the consequences of executing a check case. It is an example of the Collecting Parameter sample. The take a look at framework distinguishes among disasters and errors. A failure is predicted and checked for with assertions. Errors are unanticipated problems like an ArrayIndexOutOfBoundsException.


Q25. What is JWebUnit?

Ans: WebUnit is a Java-based totally trying out framework for net packages. It wraps existing trying out frameworks consisting of HtmlUnit and Selenium with a unified, easy checking out interface to allow you to quick take a look at the correctness of your net applications.


Q26. What are the blessings of using JWebUnit?

Ans: JWebUnit provides a high-degree Java API for navigating an internet software combined with a fixed of assertions to affirm the software's correctness. This consists of navigation through links, form access and submission, validation of table contents, and different normal commercial enterprise web application functions.

The easy navigation techniques and ready-to-use assertions permit for extra speedy test advent than the usage of best JUnit or HtmlUnit. And in case you need to switch from HtmlUnit to different plugins which includes Selenium (to be had quickly), there's no need to rewrite your tests.

Q27. Why does JUnit most effective document the primary failure in a unmarried take a look at?

Ans: There is not any specific answer for this question, the main purpose it does it like this to make the testing method simple and easy. Even even though the failures are multiple it best reviews the first failure, resolving which may also implicitly remedy other unreported disasters too.

Q28. Is it possible to skip command-line arguments to a test execution?

Ans: Yes, It’s feasible to pass command line arguments to a test execution.

You should use this command:

-D JVM command-line alternatives.

Q29. Can we exchange go back kind of JUnit take a look at approach from void to a few other kind?

Ans: Ideally you should not do this. All the JUnit take a look at techniques have to have a void return type. If you change the return type then the test method could no longer be taken into consideration as a take a look at approach and could be ignored all through execution of assessments.

Q30. The methods Get () and Set () must be tested for which situations?

Ans: Unit checks accomplished on java code should be designed to goal regions that might ruin. Since the set() and get() strategies on easy facts sorts are unlikely to break, there may be no need to check them explicitly. On the alternative hand, set() and get() methods on complex facts sorts are prone to interrupt. So they ought to be tested.