jacoco.gradle

project.afterEvaluate {
    // Grab all build types and product flavors
    def buildTypes = android.buildTypes.collect { type -> type.name }
    def productFlavors = android.productFlavors.collect { flavor -> flavor.name }

    // When no product flavors defined, use empty so that the for loop below can continue.
    if (!productFlavors) productFlavors.add('')

    productFlavors.each { productFlavorName ->
        buildTypes.each { buildTypeName ->
            def sourceName, sourcePath
            if (!productFlavorName) {
                sourceName = sourcePath = "${buildTypeName}"
            } else {
                sourceName = "${productFlavorName}${buildTypeName.capitalize()}"
                sourcePath = "${productFlavorName}/${buildTypeName}"
            }
            def testTaskName = "test${sourceName.capitalize()}UnitTest"
            def unitTestCoverageTaskName = "${testTaskName}Coverage"

            def excludedFiles = fileTree(
                    dir: "${project.buildDir}/**/intermediates/javac/${sourcePath}",
                    excludes: [
                            '**/R.class', // Android generated classes
                            '**/R$*.class', // Android generated classes
                            '**/*Dagger*.*', // Dagger auto-generated code.
                            '**/*MembersInjector*.*', // Dagger auto-generated code.
                            '**/*_ViewBinding*.*', // Butterknife auto-generated code.
                            '**/AutoValue_*.*', // AutoValue auto-generated code.
                            '**/R2.class', // Butterknife auto-generated code.
                            '**/R2$*.class', // Butterknife auto-generated code.
                            '**/BuildConfig.*',
                            //...
                    ]
            )

            // Create coverage task for unit tests of form 'test<Flavor><BuildType>Coverage' depending on 'test<Flavor><BuildType>UnitTest'
            task "${unitTestCoverageTaskName}"(type: JacocoReport, dependsOn: "$testTaskName") {
                group = 'Reporting'
                description = "Generate Jacoco coverage reports for the ${sourceName.capitalize()} build. Only unit tests."

                def coverageSourceDirs = [
                        'src/main/java',
                        "src/$productFlavorName/java",
                        "src/$buildTypeName/java"
                ]
                classDirectories = excludedFiles
                additionalSourceDirs = files(coverageSourceDirs)
                sourceDirectories = files(coverageSourceDirs)
                executionData = files("${project.buildDir}/jacoco/${testTaskName}.exec")

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

}