Jacoco setup for calculating kotlin test coverage (single module)

README.md

Jacoco setup for calculating kotlin test coverage (single module)

put the jacoco.gradle file below somewhere in your app repo (like scripts folder), and then add apply from: '../scripts/jacoco.gradle' to your module gradle file.

This will add additional gradle build tasks to your app, in the form of "testFlavourUnitTestCoverage" that you can run manually (e.g. testStagingDebugUnitTestCoverage) to generate the coverage.

You can edit def excludes definition to further exclude classes you don't want to generate the coverage for. If you have source in other folders beyond those specified in def coverageSourceDirs, add them.

This will generate both exec file used by external code quality analyzers (like Sonarqube), in the build/jacoco folder, and XML and HTML reports, in the build/reports/jacoco/flavourName folder.

You can then click through the links in the report and arrive at the annotated code to see exactly which lines are not covered by tests.

jacoco.gradle

apply plugin: 'jacoco'

jacoco {
    toolVersion = "0.8.6"
}

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
    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"

            // Create coverage task of form 'testFlavorTypeCoverage' depending on 'testFlavorTypeUnitTest'
            task "${testTaskName}Coverage" (type:JacocoReport, dependsOn: "$testTaskName") {
                group = "Reporting"
                description = "Generate Jacoco coverage reports on the ${sourceName.capitalize()} build."

                def excludes = [
                        '**/R.class',
                        '**/R$*.class',
                        '**/Manifest*.*',
                        'android/**/*.*',
                        '**/BuildConfig.*',
                        '**/*$ViewBinder*.*',
                        '**/*$ViewInjector*.*',
                        '**/Lambda$*.class',
                        '**/Lambda.class',
                        '**/*Lambda.class',
                        '**/*Lambda*.class'
                ]

                getClassDirectories().setFrom(fileTree(
                        dir: "${project.buildDir}/intermediates/classes/${sourcePath}",
                        excludes: excludes
                ) + fileTree(
                        dir: "${project.buildDir}/tmp/kotlin-classes/${sourceName}",
                        excludes: excludes
                ))

                def coverageSourceDirs = [
                        "src/main/java",
                        "src/$productFlavorName/java",
                        "src/$buildTypeName/java"
                ]
                getAdditionalSourceDirs().setFrom(files(coverageSourceDirs))
                getSourceDirectories().setFrom(files(coverageSourceDirs))
                getExecutionData().setFrom(files("${project.buildDir}/jacoco/${testTaskName}.exec"))

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

Hi Jackie,
I see you've been struggling with this, I have a working example on my github here.
https://github.com/bveenvliet/JacocoTestCoverage