JUnit 5 Installation Guide for Eclipse: Download and Configure JUnit Jar Files

How to Download and Install JUnit 5 Jar for Eclipse

JUnit is one of the most popular unit testing frameworks for Java. It helps developers write, run, and debug tests easily and efficiently. JUnit 5 is the latest version of JUnit, which introduces many new features and improvements over its predecessor, JUnit 4.

download junit 5 jar for eclipse

In this article, we will learn how to download and install JUnit 5 jar for Eclipse, a widely used integrated development environment (IDE) for Java. We will also see how to write and run a simple test with JUnit 5.

Before we begin, we need to make sure that we have the following prerequisites:

• Java Development Kit (JDK) version 8 or higher installed on our system.

• Eclipse IDE version Oxygen or higher installed on our system.

Downloading JUnit 5 jars

There are two ways to download JUnit 5 jars: from the official website or from Maven Central Repository.

How to download, install and configure junit in eclipse

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How to download JUnit 5 jars from the official website?

To download JUnit 5 jars from the official website, we need to follow these steps:

• Visit [1](https://junit.org/junit5/) and click on Download and Install.

• Click on junit-platform-console-standalone.jar. This is a single jar file that contains all the necessary components for running tests with JUnit Platform.

• Save the jar file in a folder of our choice. For example, we can create a folder named junit5 in our C:\ drive and save the jar file there.

How to download JUnit 5 jars from Maven Central Repository?

To download JUnit 5 jars from Maven Central Repository, we need to follow these steps:

• Visit [2](https://search.maven.org/search?q=g:org.junit.jupiter) and search for org.junit.jupiter. This is the group ID for JUnit Jupiter, which is the main API for writing tests with JUnit 5.

• Select the latest version of junit-jupiter-api. This is the artifact ID for the core library that provides annotations and assertions for writing tests with JUnit Jupiter.

• Click on jar link under Download column. Save the jar file in the same folder where we saved the previous jar file.

• Repeat steps 2 and 3 for junit-jupiter-engine. This is the artifact ID for the test engine that runs tests written with JUnit Jupiter.

• Visit [3](https://search.maven.org/search?q=g:org.junit.platform) and search for org.junit.platform. This is the group ID for JUnit Platform, which provides a common foundation for running tests with different frameworks.

• Select the latest version of junit-platform-launcher. This is the artifact ID for the library that provides a launcher API for launching tests with JUnit Platform.

• Click on jar link under Download column. Save the jar file in the same folder where we saved the previous jar files.

Setting up environment variables

To run tests with JUnit 5, we need to set up two environment variables: JUNIT_HOME and CLASSPATH.

How to set up JUNIT_HOME and CLASSPATH variables?

To set up JUNIT_HOME and CLASSPATH variables, we need to follow these steps:

• Right-click on My Computer and select Properties.

• Click on Advanced system settings.

• Click on Environment Variables.

• Under System variables, click on New.

• In the Variable name field, enter JUNIT_HOME.

• In the Variable value field, enter the path of the folder where we saved the JUnit 5 jar files. For example, C:\junit5.

• Click on OK.

• Select the CLASSPATH variable from the list of system variables. If it does not exist, create a new one as before.

• Edit the CLASSPATH variable and append the following value to it: ; %JUNIT_HOME%\junit-platform-console-standalone.jar; %JUNIT_HOME%\junit-jupiter-api.jar; %JUNIT_HOME%\junit-jupiter-engine.jar; %JUNIT_HOME%\junit-platform-launcher.jar;. The semicolons are used to separate different paths in the classpath.

• Click on OK.

• Click on OK again to close the environment variables window.

• Restart Eclipse IDE if it is already running.

How to verify the environment variables?

To verify the environment variables, we can use the following steps:

• Open a command prompt window.

• Type echo %JUNIT_HOME% and press enter. It should display the path of the folder where we saved the JUnit 5 jar files.

• Type echo %CLASSPATH% and press enter. It should display the classpath value that includes the JUnit 5 jar files.

• Type junit-platform-console-standalone --version. It should display the version of JUnit Platform Console Standalone that we downloaded.

Configuring Eclipse IDE

To use JUnit 5 in Eclipse IDE, we need to configure two things: adding JUnit 5 jars to the build path of a project and enabling JUnit 5 support in Eclipse preferences.

How to add JUnit 5 jars to the build path of a project?

To add JUnit 5 jars to the build path of a project, we need to follow these steps:

• Create a new Java project in Eclipse or open an existing one.

• Select the project from the Package Explorer and right-click on it. Select Properties.

• Select Java Build Path.

• Select Add External JARs....

• Browse to the folder where we saved the JUnit 5 jar files and select all of them. Click on Open.

• The selected jar files should appear under JRE System Library. Click on Apply and Close.

How to enable JUnit 5 support in Eclipse preferences?

To enable JUnit 5 support in Eclipse preferences, we need to follow these steps:

• Select window > Preferences

• SelectJAVA > Installed JREs

• SelectEdit

• SelectAdd External JARs...

• Browse to the folder where we saved the JUnit 5 jar files and select all of them. Click onAdd

• The selected jar files should appear underJRE system libraries . Click onFinnish Click on OK to close the preferences window.

Writing and running a simple test

Now that we have downloaded and installed JUnit 5 jar for Eclipse, we can write and run a simple test with JUnit 5.

How to create a test class with JUnit 5 annotations?

To create a test class with JUnit 5 annotations, we need to follow these steps:

• Create a new Java class in the project. For example, we can name it CalculatorTest.

Import the following packages at the top of the class: import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.*;

• These packages provide the @Test annotation and the assertion methods for writing tests with JUnit 5.

Create a test method with the @Test annotation. For example, we can write a test method that checks if the addition of two numbers is correct: @Test

public void testAdd()

// Arrange

Calculator calculator = new Calculator();

// Act

int result = calculator.add(2, 3);

// Assert

assertEquals(5, result);

• The @Test annotation indicates that this method is a test case. The assertEquals(expected, actual) method asserts that the expected value and the actual value are equal. If they are not equal, the test fails.

• We can create more test methods with different scenarios and assertions as needed.

How to run a test with JUnit 5 platform?

To run a test with JUnit 5 platform, we need to follow these steps:

• Select the test class from the Package Explorer and right-click on it. Select Run As > JUnit Test.

• Eclipse will launch the JUnit 5 platform and run the test methods in the test class.

• The results of the test execution will be displayed in the JUnit view. We can see if the tests passed or failed, how long they took, and what errors or failures occurred.

• We can also run individual test methods by selecting them from the Outline view and right-clicking on them. Select Run As > JUnit Test.

Conclusion

In this article, we learned how to download and install JUnit 5 jar for Eclipse. We also learned how to write and run a simple test with JUnit 5. JUnit 5 is a powerful and flexible testing framework that offers many benefits over its previous versions. It supports multiple testing engines, lambda expressions, nested tests, parameterized tests, dynamic tests, extensions, and more. It also integrates well with other testing frameworks and tools such as Mockito, Selenium, Spring Boot, etc.

If you want to learn more about JUnit 5, you can visit the following links:

• [4](https://junit.org/junit5/docs/current/user-guide/) - The official user guide for JUnit 5.

• [5](https://www.baeldung.com/junit-5) - A comprehensive tutorial on JUnit 5 by Baeldung.

• [6](https://www.vogella.com/tutorials/JUnit/article.html) - A practical guide on JUnit 5 by Vogella.

FAQs

Here are some frequently asked questions about JUnit 5:

What are some of the new features of JUnit 5?

Some of the new features of JUnit 5 are:

• A modular architecture that consists of three main components: JUnit Platform, JUnit Jupiter, and JUnit Vintage.

• A new annotation-based programming model that supports meta-annotations, composed annotations, repeated annotations, display names, tags, etc.

• A new assertion API that supports lambda expressions, assumptions, grouped assertions, etc.

• A new extension model that allows customizing test execution behavior through various extension points such as lifecycle callbacks, parameter resolvers, exception handlers, etc.

• A new launcher API that enables launching tests from different IDEs, build tools, or custom code.

• A new console launcher that allows running tests from the command line.

• A new discovery mechanism that allows finding tests from different sources such as classpath, directories, files, modules, etc.

• A new test engine API that allows implementing test engines for different testing frameworks such as JUnit 4, TestNG, Spock, etc.

How to migrate from JUnit 4 to JUnit 5?

To migrate from JUnit 4 to JUnit 5, we need to follow these steps:

• Download and install JUnit 5 jar for Eclipse as described in this article.

• Add the junit-vintage-engine jar file to the build path of the project. This jar file provides a test engine that runs tests written with JUnit 4 on the JUnit Platform.

• Replace the @RunWith annotation with the @ExtendWith annotation and use the corresponding extension class. For example, replace @RunWith(MockitoJUnitRunner.class) with @ExtendWith(MockitoExtension.class).

• Replace the @Rule and @ClassRule annotations with the @RegisterExtension annotation and use the corresponding extension class. For example, replace @Rule public TemporaryFolder folder = new TemporaryFolder(); with @RegisterExtension public TemporaryFolderExtension folder = new TemporaryFolderExtension();.

• Replace the @Test(expected = ...) and @Test(timeout = ...) annotations with the assertThrows and assertTimeout methods respectively. For example, replace @Test(expected = IllegalArgumentException.class) with assertThrows(IllegalArgumentException.class, () -> ...);.

• Replace the @Ignore annotation with the @Disabled annotation.

• Replace the @Category annotation with the @Tag annotation.

• Replace the @BeforeClass, @AfterClass, @Before, and @After annotations with the @BeforeAll, @AfterAll, @BeforeEach, and @AfterEach annotations respectively.

• Migrate any custom runners, rules, or matchers to use the JUnit 5 extension model.

• Migrate any test suites to use the JUnit Platform Suite Engine.

How to use JUnit 5 with other testing frameworks and tools?

To use JUnit 5 with other testing frameworks and tools, we need to use the appropriate test engine or extension that supports them. For example:

• To use JUnit 5 with Mockito, we need to use the MockitoExtension class that provides support for mocking and spying.

• To use JUnit 5 with Selenium, we need to use the SeleniumExtension class that provides support for managing WebDriver instances.

• To use JUnit 5 with Spring Boot, we need to use the SpringExtension class that provides support for loading application context and injecting dependencies.

• To use JUnit 5 with TestNG, we need to use the TestNGEngine class that provides a test engine for running TestNG tests on the JUnit Platform.

• To use JUnit 5 with Spock, we need to use the SpockEngine class that provides a test engine for running Spock tests on the JUnit Platform.

How to write parameterized and dynamic tests with JUnit 5?

To write parameterized and dynamic tests with JUnit 5, we need to use the following annotations and methods:

To write parameterized tests, we need to use the @ParameterizedTest annotation instead of the @Test annotation. We also need to provide a source of arguments for the test method using annotations such as@ValueSource,@CsvSource,@MethodSource, etc. We can access the arguments using parameters or arguments accessors in the test method. For example:

• This test method will run three times with different values of number: 2, 4, and 6.

To write dynamic tests, we need to use the@TestFactory annotation instead of the@Test dynamicTest, dynamicContainer, etc. We can generate the dynamic tests based on any logic or data source. For example: testPalindrome() List words = Arrays.asList("racecar", "level", "kayak", "rotor", "madam"); return words.stream() .map(word -> dynamicTest("Is " + word + " a palindrome?", () -> assertTrue(isPalindrome(word)))) .collect(Collectors.toList());

• This test method will return five dynamic tests, each checking if a word is a palindrome.

How to use JUnit 5 extensions for customizing test execution?

To use JUnit 5 extensions for customizing test execution, we need to use the @ExtendWith annotation and provide one or more extension classes. An extension class is a class that implements one or more extension interfaces that define various extension points. For example:

• To customize the test instance lifecycle, we can implement the TestInstanceFactory or TestInstancePostProcessor interface.

• To customize the test parameter resolution, we can implement the ParameterResolver interface.

• To customize the test execution condition, we can implement the ExecutionCondition interface.

• To customize the test exception handling, we can implement the TestExecutionExceptionHandler interface.

• To customize the test lifecycle callbacks, we can implement the BeforeAllCallback, BeforeEachCallback, AfterEachCallback, or AfterAllCallback interface.

• To customize the test reporting, we can implement the TestReporter interface.

We can apply the @ExtendWith annotation at the class level or at the method level. We can also create our own custom annotations that are meta-annotated with @ExtendWith. For example:

This annotation will apply the TimingExtension class to any test class or method that is annotated with @Timed. The TimingExtension class is an extension that measures and reports the execution time of each test.