Step-by-Step Guide: Adding JaCoCo to a Maven Project

In this comprehensive guide, we’ll walk through the integration process of JaCoCo, a popular Java code coverage library, into your Maven project. By following these step-by-step instructions, you’ll effectively measure test coverage and ensure the quality of your Java applications.

Why Use JaCoCo for Code Coverage?

JaCoCo is a powerful tool that provides detailed insights into your codebase’s test coverage. By analyzing which parts of your code are executed during testing, this tool helps identify areas that may require additional testing, leading to improved code quality and reliability.

Prerequisites

Before we begin, ensure you have the following prerequisites in place:

• Java Development Kit (JDK) installed on your system
• Apache Maven installed and configured

Step 1: Adding JaCoCo Plugin to Your Maven Project

Open your Maven project’s pom.xml file and add the plugin configuration within the <build> section:

<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.8.12</version>
    <executions>
        <execution>
            <goals>
                <goal>prepare-agent</goal>
            </goals>
        </execution>
        <!-- attached to Maven test phase -->
        <execution>
            <id>report</id>
            <phase>test</phase>
            <goals>
                <goal>report</goal>
            </goals>
        </execution>
    </executions>
</plugin>

This configuration adds the plugin to your Maven build process, enabling code coverage analysis.

Step 2: Running Tests with JaCoCo

Run your Maven tests to generate code coverage reports. Use the following Maven command:

mvn clean test

This command executes your tests while collecting coverage data.

Step 3: Viewing Code Coverage Reports

After running the tests, JaCoCo generates code coverage reports in the target/site/jacoco directory of your Maven project. Open the HTML report (index.html) in a web browser to view detailed coverage metrics for your codebase.

Conclusion

Congratulations! You’ve successfully integrated JaCoCo into your Maven project and generated code coverage reports. By regularly analyzing these reports, you can track your code’s test coverage and make informed decisions to improve overall code quality.

You can download a version of the code showcased in this article from my GitHub repository.

If you want to verify the code coverage of your Kotlin code, look at Step-by-Step Guide: Adding Kotlin to Your Maven Project.

Stay tuned for more tutorials and tips on Java development and code quality. Thank you for reading this article!