How to Generate Code Coverage Reports with JaCoCo

How do I run jacocoReport to generate code coverage reports in my Java project?

mvn jacoco:prepare-agent test jacoco:report

JaCoCo (Java Code Coverage) is a library that enables the generation of code coverage reports. It is commonly used in Java projects to track the effectiveness of unit tests. In this guide, we will explore how to run the jacocoReport goal to produce detailed code coverage reports after running your tests.

<build>
    <plugins>
        <plugin>
            <groupId>org.jacoco</groupId>
            <artifactId>jacoco-maven-plugin</artifactId>
            <version>0.8.7</version>
            <executions>
                <execution>
                    <goals>
                        <goal>prepare-agent</goal>
                    </goals>
                </execution>
                <execution>
                    <id>report</id>
                    <phase>test</phase>
                    <goals>
                        <goal>report</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Causes

• Missing JaCoCo plugin in Maven POM file.
• Tests not executed before generating the report.
• Incorrect configuration of JaCoCo execution data.

Solutions

• Ensure that the JaCoCo plugin is added to your Maven POM file.
• Run your tests using Maven before generating the report: `mvn test`
• Check the configuration for JaCoCo in your POM to make sure it's set up correctly.

Mistake: Not including the JaCoCo dependency in the project.

Solution: Add the JaCoCo plugin to the `<build>` section of the POM.

Mistake: Running the jacocoReport goal without executing tests first.

Solution: Always run `mvn test` before `mvn jacoco:report`.

Mistake: Ignoring the target directory for the generated reports.

Solution: Check the target directory (`target/site/jacoco`) for the generated code coverage reports.