Test code coverage in GitLab CI

pom.xml

To compute test code coverage, whenever someone pushes to the git repository:

1 - First add the following two plugins to the <plugins> section of your pom.xml.
  The Surefire plugin executes unit tests, and the Jacoco plugin will compute test coverage:
  
  <plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.7.7.201606060606</version>
    <executions>
      <execution>
        <id>pre-unit-test</id>
        <goals><goal>prepare-agent</goal></goals>
        <configuration>
          <destFile>${project.build.directory}/coverage-reports/jacoco-ut.exec</destFile>
          <propertyName>surefireArgLine</propertyName>
        </configuration>
      </execution>
      <execution>
        <id>post-unit-test</id>
        <phase>test</phase>
        <goals><goal>report</goal></goals>
        <configuration>
          <dataFile>${project.build.directory}/coverage-reports/jacoco-ut.exec</dataFile>
          <outputDirectory>${project.reporting.outputDirectory}/jacoco-ut</outputDirectory>
        </configuration>
      </execution>
    </executions>
  </plugin>
  
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
      <argLine>${surefireArgLine}</argLine>
      <skipTests>${skip.unit.tests}</skipTests>
    </configuration>
  </plugin>

2 - Next, add these two entries to the <properties> section of pom.xml. 
  This will ensure that test coverage results are also uploaded to the SonarQube server:
  
  <sonar.junit.reportsPath>target/surefire-reports</sonar.junit.reportsPath>
  <sonar.jacoco.reportPath>target/coverage-reports/jacoco-ut.exec</sonar.jacoco.reportPath>
  
3 - Done! Push your changes to the git repository, then wait for the continuous integration build to finish.
  Once this is done, you can browse test coverage results at the SonarQube server: http://wilma.vub.ac.be:9000