README.md

jacoco-report-maven-plugin

This Maven plugin processes JaCoCo execution data and produces coverage reports that can then be uploaded to codecov.io. The main difference with respect to other tools is that it correctly computes cross-module coverage in multi-module Maven builds.

To use the plugin, add the following to your project's root POM:

<plugin>
    <groupId>com.github.veithen.maven</groupId>
    <artifactId>jacoco-report-maven-plugin</artifactId>
    <version>x.y.z</version>
    <executions>
        <execution>
            <goals>
                <goal>process</goal>
            </goals>
        </execution>
    </executions>
</plugin>

This would be used in conjunction with the standard jacoco-maven-plugin to generate the execution data that is processed by jacoco-report-maven-plugin:

<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.8.2</version>
    <executions>
        <execution>
            <goals>
                <goal>prepare-agent</goal>
            </goals>
        </execution>
    </executions>
</plugin>

With Github Actions you can then upload the coverage report using a configuration like this:

- name: Upload Coverage Report
  uses: codecov/codecov-action@v4
  with:
    fail_ci_if_error: true
    files: ./target/coverage.json
    token: ${{ secrets.CODECOV_TOKEN }}

You might want to exclude the code from some modules from the coverage reports, e.g. modules that contain test utilities. In this case, set the includeClasses parameter to false for those modules:

<plugin>
    <groupId>com.github.veithen.maven</groupId>
    <artifactId>jacoco-report-maven-plugin</artifactId>
    <configuration>
        <includeClasses>false</includeClasses>
    </configuration>
</plugin>

If your project provides a Maven plugin and has integration tests set up with maven-invoker-plugin, use the following configuration to collect coverage data from those integration tests:

<pluginManagement>
    <plugins>
        <plugin>
            <artifactId>maven-invoker-plugin</artifactId>
            <version>3.1.0</version>
            <configuration>
                <mavenOpts>${argLine}</mavenOpts>
            </configuration>
        </plugin>
    </plugins>
</pluginManagement>