To add JUnit to a Maven project, you add the JUnit dependency to your project’s pom.xml, create test classes under src/test/java, and run the tests with Maven.

1. Add JUnit to pom.xml

For modern Java projects, use JUnit 5.

<dependencies>
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter</artifactId>
        <version>5.13.4</version>
        <scope>test</scope>
    </dependency>
</dependencies>

If your pom.xml already has a <dependencies> section, add only the <dependency> block inside it.

2. Configure Maven Surefire Plugin

JUnit tests are usually run by the Maven Surefire Plugin. Add this inside the <build> section of your pom.xml:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>3.5.3</version>
        </plugin>
    </plugins>
</build>

If your project already has a <build> or <plugins> section, merge the plugin into the existing structure instead of duplicating it.

3. Create a Test Class

Maven expects test classes to be placed under:

src/test/java

Example project structure:

my-project
├── pom.xml
└── src
    ├── main
    │   └── java
    │       └── org
    │           └── kodejava
    │               └── Calculator.java
    └── test
        └── java
            └── org
                └── kodejava
                    └── CalculatorTest.java

Example class to test:

package org.kodejava;

public class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
}

Example JUnit 5 test:

package org.kodejava;

import org.junit.jupiter.api.Test;

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

class CalculatorTest {

    @Test
    void addShouldReturnSum() {
        Calculator calculator = new Calculator();

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

        assertEquals(5, result);
    }
}

4. Run the Tests

From the project directory, run:

mvn test

Maven will compile your code, compile your tests, and run any matching test classes.

Common test class naming patterns include:

*Test.java
*Tests.java
*TestCase.java

Complete pom.xml Example

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>org.kodejava</groupId>
    <artifactId>junit-maven-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.release>25</maven.compiler.release>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>5.13.4</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>3.5.3</version>
            </plugin>
        </plugins>
    </build>

</project>

That’s it — after adding the dependency and plugin configuration, you can start writing JUnit tests and run them with mvn test.