Demo project for aggregating Jacoco Android & JVM coverage reports

This is an example project that illustrates how can the JaCoCo Report Aggregation Plugin and Test Report Aggregation Plugin can be used to aggregate a complex Android project with JVM modules in a single :jacocoTestReport and :testAggregateTestReport tasks.

Project structure

• An app android module (with Robolectric tests)
• A login android library module (with JUnit4/JVM tests)
• A domain jvm module (with tests)
• A coverage-plugin included build that provides the coverage root plugin

The coverage root plugin

The plugin fills the gaps between AGP and JaCoCo Report Aggregation Plugin by providing the necessary setup missing:

• It applies jacoco-report-aggregation and test-report-aggregation at root project
• Creates jacocoTestReport and testAggregateTestReport for TestSuiteType.UNIT_TEST
• If a module applies jacoco plugin, it adds it to the jacocoAggregation and testReportAggregation root configurations
• If a module applies the java plugin, makes its child jacocoTestReport task to depend on test
• If a module applies the android plugin:
  • it enables by default BuildType.enableUnitTestCoverage on debug to produce jacoco exec files
  • adds the codeCoverageExecutionData, codeCoverageSources, codeCoverageElements (classes) and testResultsElements outgoing variants, to allow jacoco-report-aggregation and test-report-aggregation to aggregate it

Please note that JVM still need to manually apply jacoco plugin (this is an intentional opt-in behavior) build.gradle.kts

Producing an aggregated report for the whole project

The task :jacocoTestReport is added to the root project when applying this plugin and it can be run to produce the report. All dependent test tasks will be run too to produce the required execution data.

The same for :testAggregateTestReport:

Use the coverage plugin on your own project

The easiest way to adopt this plugin, is to put the coverage.gradle.kts on your buildSrc/src/main/kotlin folder. Create the buildSrc project if missing and make sure to apply kotlin-dsl plugin on it

Don't forget its companion CoveragePluginDSL.kt file

The aggregateTestCoverage DSL extension

This is an opt-in/out switch meant to be used when having productFlavors.

enableUnitTestCoverage is a BuildType setting (default on debug). When having flavors, you'll have many coverage reports to produce targeting debug (one per flavor variant). You can use enableUnitTestCoverage.set(false) to turn aggregation off for an specific ProductFlavor. Basically, the variant won't be added to the codeCoverageExecutionData configuration, so :jacocoTestReport won't compute it

For instance, app module has a environment dimension with 2 flavors: stage and prod. Without any extra settings, :jacocoTestReport will depend on :app:testStageDebugUnitTest and :app:testProdDebugUnitTest (running its src/test/ tests effectively twice). You may choose which flavors participates in the aggregated report by doing:

    productFlavors {
        create("stage") { 
            dimension = "environment" 
        }
        create("prod") { 
            dimension = "environment"
            aggregateTestCoverage.set(false)
        }
    }

where it effectively only run :app:testStageDebugUnitTest