JUnit is a simple, open-source framework to write and run repeatable tests in Java. It's an essential tool for any serious developer who wants to implement unit testing into their development lifecycle. Here's how you can integrate JUnit into your Maven project.

Prerequisites

Before proceeding, make sure you have:

• Java JDK installed (Java 8 or later)
• Apache Maven installed

Step 1: Updating the pom.xml File

The first step to adding JUnit to your Maven project is to update your project's pom.xml file. This XML file describes the software project being built, its dependencies, and the build order.

You can include JUnit in your project by adding it as a dependency. Here is how you do that:

In the example above, I'm using JUnit version 5.9.3. You can change the version number to whichever version of JUnit you'd like to use.

The <scope> tag is used to limit the transitivity of a dependency. In this case, it's set to test, meaning this dependency is not required for normal use of the application, and is only available for the test compilation and execution phases.

Step 2: Writing Test Cases

Once the pom.xml file is updated, you can begin writing your test cases. By convention, test cases are placed in the src/test/java directory.

Here is an example of a simple test case:

In this test case, we're importing the JUnit Test annotation, and we're using it to denote a test method testAddition(). The assertEquals() method is a JUnit assertion that checks if two values are equal. If they are not, the test fails.

Step 3: Running Tests

You can run the tests using the Maven command: mvn test. Maven will automatically run any test cases that it finds in the src/test/java directory.

You should see output similar to the following if the tests pass:

The output indicates that one test was run and that there were no failures, errors, or skipped tests.

In conclusion, adding JUnit to your Maven project is a straightforward task that can greatly enhance the quality and maintainability of your code by making it easy to write and run tests. Happy testing!

Reading List

• Baeldung Junit5 Guide
• Junit5 User Guide