[Project combat] Use the Maven plug-in (jacoco-maven-plugin) to generate code coverage reports

1. What is jacoco-maven-plugin?

jacoco-maven-plugin is a Maven plugin for generating code coverage reports.
It can help you understand which parts of your code are already covered by tests and which parts need more testing.
Note that the jacoco-maven-plugin requires Java 1.5 or higher to run.

2. Steps to generate code coverage report using jacoco-maven-plugin:

2.1 Add the maven plugin to the pom.xml file

To use jacoco-maven-plugin, you need to add the following configuration to the Maven project:

<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>

This will configure the plugin to run in the test phase of Maven builds and generate reports in the target/site/jacoco directory.

In the above configuration, the version number of jacoco-maven-plugin is specified, and two execution phases are defined.

• 1. (prepare-agent) Add the Jacoco agent to the JVM to collect code coverage information when running tests.
• 2. (report) will generate a code coverage report.

2.2 Running a Maven build with the test goal

To generate a code coverage report, you can run the following Maven command:

mvn test

This will execute your tests and generate a code coverage report.

2.3 View code coverage report

The report will be located in target/site/jacoco/index.html file.
Open the index.html file in the target/site/jacoco directory in a web browser to view the code coverage report.