Aggregate Report for Gradle Multi-Project build

Question

I need to create an aggregate code coverage report for my multiple-module Gradle project using the JaCoCo plugin for Gradle, similar to the one generated by the jacoco:aggregate-report of Maven's jaoco-maven-plugin .

I have been googling for a solution the last couple of days but nothing has worked so far. Most of the proposed solutions involve defining a task of type JacocoReport in the root project, that aggregates the execution data and produces the html code coverage report. However everything I tried so far either fails with an error or does not generate any report.

For example, this code snippet that I have tried:

def publishedProjects = subprojects.findAll()

task jacocoRootReport(type: JacocoReport) {

    dependsOn(publishedProjects.test)

    additionalSourceDirs = files(publishedProjects.sourceSets.main.allSource.srcDirs)
    sourceDirectories = files(publishedProjects.sourceSets.main.allSource.srcDirs)
    classDirectories = files(publishedProjects.sourceSets.main.output)
    executionData = files(publishedProjects.jacocoTestReport.executionData)

    doFirst {
        executionData = files(executionData.findAll { it.exists() })
    }

    reports {
        html.enabled = true
        xml.enabled = false
    }
}

gives the error groovy.lang.GroovyRuntimeException: Cannot set the value of read-only property 'additionalSourceDirs' for task ':jacocoRootReport' of type org.gradle.testing.jacoco.tasks.JacocoReport

The version of Gradle that I am using is 7.3. Unfortunately I'm very new to Gradle and I still cannot fiddle with the code snippets that I've found to make them work for my case.

Any help will be much appreciated. Thank you very much in advance.

Answer 1

There is an official example in the Gradle docs for this use case:

https://docs.gradle.org/7.3.3/samples/sample_jvm_multi_project_with_code_coverage.html

It is a somewhat complex and requires an additional project that will serve as the aggregate. The way you have above is generally discouraged by Gradle for reasons outside of this question/answer.