Reporting and Merging multi-module jacoco reports with report-aggregate

Question

Attempting to get one jacoco report that will show all the results from multiple modules.

I am able to see that each of the sub-modules have an jacoco.exec after building the project but unsure of how to get it to output one report that will have all the results from every module combined.

This is what I have included in my Root pom.xml:

                <plugin>
                    <groupId>@project.groupId@</groupId>
                    <artifactId>jacoco-maven-plugin</artifactId>
                    <version>@project.version@</version>
                </plugin>



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

I created a new module explicitly for reporting purposes. (e.g. report-aggregate-module)

Deleted the group ids and used generic artifact ids for this example:

This is what I put in the pom.xml for this report-aggregate sub-module:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <artifactId>report-aggregate</artifactId>
        <groupId>com.name.group</groupId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>


    <artifactId>report-aggregate</artifactId>
    <name>Report Aggregate</name>

    <properties>
        <wildfly.version>10.0.0.Final</wildfly.version>
        <wildfly.artifactId>wildfly-dist</wildfly.artifactId>
    </properties>

    <dependencies>
        <dependency>
            <groupId></groupId>
            <artifactId>sub-module1</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>sub-module2</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>sub-module3</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>sub-module4</artifactId>
            <version>${project.version}</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.jacoco</groupId>
                <artifactId>jacoco-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <id>report-aggregate</id>
                        <phase>verify</phase>
                        <goals>
                            <goal>report-aggregate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Everything seems to compile okay, the jacoco exec doesn't seem to get created for the report-aggregate-module. Anyone know a solution to this or if I'm doing this incorrectly?

Answer 1

Sorry if this comes a late answer.

I assume that your root pom.xml is an aggregater, with <modules> consisting of module1, module2, and report-aggregate. This is the cause of your trouble: as your root pom.xml is an aggregator, it runs JaCoCo BEFORE your submodules do, so your final report is empty. You should:

• Move the configuration of goal report-aggregate of the jacoco-maven-plugin from the root POM to the report-aggregate POM. This should do the trick, because your report-aggregate POM uses <dependencies>, not <modules>.
• Keep the configuration of goal prepare-agent of the jacoco-maven-plugin in the root POM.

I suggest you look at the JaCoCo forum https://groups.google.com/forum/#!topic/jacoco/FpdLbxsXSTY. It refers to a complete demo integration test https://github.com/jacoco/jacoco/tree/master/jacoco-maven-plugin.test/it/it-report-aggregate.