[FIXED] Jacoco is reporting 0 coverage of Kotlin classes by unit tests, in an Android project

Issue

I'm using Android Gradle Plugin 3.0.0.

I'm migrating an Android app from java to kotlin. My app has classes in Java and Kotlin, and tests are in Java.

I run ./gradlew clean jacocoTestReport.

This runs both unit tests (src/test) and instrumentation tests (src/androidTest).

The report produced by jacoco in app/build/reports/jacoco/jacocoTestReport/html/index.html doesn't show coverage for Kotlin classes which are indeed covered by unit tests.

The report does show coverage correctly from instrumentation tests.

Note: I came across these other questions, which aren't exactly the same issue:

• JaCoCo returning 0% Coverage with Kotlin and Android 3.0 has a problem with code coverage by instrumentation tests, not unit tests.
• Android Studio JaCoCo reports 0% coverage has a problem with code coverage from inside Android Studio, but not Kotlin-specific.

Relevant portions of my app module's build.gradle:

apply plugin: 'jacoco'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-kapt'
...
android {
    defaultConfig {
        sourceSets {
            main.java.srcDirs += "$projectDir/src/main/kotlin"
        }
    }

    testOptions {
        unitTests {
            all {
                jvmArgs '-noverify', '-ea'
            }
            includeAndroidResources = true
        }
    }
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    ....
}

jacoco {
    toolVersion '0.7.9'
}

task jacocoTestReport(type: JacocoReport, dependsOn: ["testDebugUnitTest", "createDebugCoverageReport"]) {
    reports {
        html.enabled = true
    }
    classDirectories = fileTree(
            dir: "${buildDir}",
            includes: ["tmp/kotlin-classes/debug/ca/rmen/android/poetassistant/**/*.class",
                       "intermediates/classes/debug/ca/rmen/android/poetassistant/**/*.class"],
            excludes: ["**/R.class", "**/R*.class", "**/Manifest.class", "**/Manifest*.class", "**/BuildConfig.class",
                       // ignore databinding generated code:
                       "**/ca/rmen/android/poetassistant/databinding/*.class",
                       ... other excludes ...
                       "**/ca/rmen/android/poetassistant/BR.class",
                       "**/com/android/**/*.class"])
    sourceDirectories = files("${project.projectDir}/src/main/java", "${project.projectDir}/src/main/kotlin")
    executionData = fileTree(
            dir: "${buildDir}",
            includes: [
                    "jacoco/testDebugUnitTest.exec",
                    "outputs/code-coverage/connected/*coverage.ec"
            ])
}

Solution

I had to add includeNoLocationClasses = true to my gradle file as follows, to make the jacoco report reflect the coverage of Kotlin classes by unit tests:

android {
    testOptions {
        unitTests {
            all {
                jvmArgs '-noverify', '-ea'
                jacoco {
                    includeNoLocationClasses = true
                }
            }
            includeAndroidResources = true
        }
    }
}

Note: this solution works for running tests from the command line, but I still get 0% coverage when running with coverage from inside Android Studio.

Answered By - Carmen
Answer Checked By - David Goodson (JavaFixing Volunteer)