Gradle Multi-Project & JaCoCo

copy-jacoco-data.groovy

subprojects {
    apply plugin: 'java'
    
    configurations {
        codeCoverage
    }
    
    dependencies {
        codeCoverage files("${rootProject.projectDir.path}/lib/jacocoagent.jar")
    }
    
    test {
        // JaCoCo uses an agent to do code coverage instrumentation on loading rather than instrumenting class files on disk
        // we set the jacoco property in case code needs to know that jacoco is active (otherwise some reflection tests fail)
        jvmArgs "-javaagent:${configurations.codeCoverage.singleFile}=destfile=${buildDirName}/coverage-results/jacoco.exec,sessionid=HSServ,append=false", 
                '-Djacoco=true',
                '-Xms128m',
                '-Xmx512m',
                '-XX:MaxPermSize=128m'
     }
    
    task copyCoverageData(dependsOn: test, type: Copy) {
        from "${buildDirName}/coverage-results"
        into "${rootProject.buildDir.path}/coverage-results"
        include 'jacoco.exec'
        rename 'jacoco.exec', "${project.name}.jacoco.exec"   
    }
}

coverage-report-dependencies.groovy

generateCoverageReport.dependsOn {
    subprojects.collect { project ->
        project.copyCoverageData.path
    }
}

generate-report.groovy

task generateCoverageReport << {
    ant {
        taskdef(name:'jacocoreport', classname: 'org.jacoco.ant.ReportTask') {
            classpath path: "${rootProject.projectDir.path}/lib/jacocoant.jar"
        }
        
        mkdir dir: "${buildDirName}/reports/coverage"
        
        jacocoreport {
            executiondata {
                fileset(dir: "${buildDirName}/coverage-results") {
                    include name: '*.jacoco.exec'
                }
            }
            
            structure(name: project.name) {
                
                classfiles {
                    dependsOnProjects.each { project ->
                        fileset dir: "${project.buildDir.path}/classes/main"
                    }
                }
                sourcefiles(encoding: 'CP1252') {
                    dependsOnProjects.each { project ->
                        fileset dir: "${project.projectDir.path}/src/main/java"
                    }
                }
            }
            
            xml  destfile: "${buildDirName}/reports/coverage/jacoco.xml"
            html destdir:  "${buildDirName}/reports/coverage"
        }
    }
}