android-java-coverage-merger

Gradle plugin for adding tasks that merge jacoco execution data for tests running on the Android device and on the local JVM

What problem does this solve?

To adequately test an Android application, one must usually run tests both on the DVM (on an Android device) and on a JVM. Without an external tool such as this one, you would get separate reports for both kinds of tests. This plugin solves the two-reports problem by merging them

How does it work?

For each build variant that has testCoverageEnabled, an associated task is added to run the tests, then generate the appropriate merged reports from both the local java (JVM) and tests run on the device (DVM). The correct task dependencies are created such that you must only run one gradle task in order to test on the JVM and DVM and generate the merged report.

Compatibility Concerns

Sample

Add the following config to your projects base build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    classpath {
        classpath 'com.android.tools.build:gradle:4.1.2'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.31"
        classpath 'com.fsryan.gradle.coverage:android-java-coverage-merger:0.1.0'
    }
}

You must first apply the jacoco plugin (and optionally the kotlin-android plugin) in any (sub)project for which you want to create combined reports.

apply plugin: 'com.android.application' // or com.android.library
apply plugin: 'jacoco'
apply plugin: 'kotlin-android'
apply plugin: 'android-java-coverage-merger'

// The actual version you use will depend upon your version of the android
// gradle plugin. Some versions of the android gradle plugin specify a
// jacoco version that generates incompatible execution data.  
jacoco {
    toolVersion '0.8.2' // or higher if using kotlin
}

With the below in your build.gradle, you'll receive the following tasks:

• createMergedFreeDebugReport - the task you should run when you want to test the free debug variant
• mergeFreeDebugReport - the merging task for the free debug variant
• jacocoFreeDebugJvmReport - the JVM-only jacoco report for the freeDebug variant--uses the class filters you have configured
• jacocoFreeReleaseJvmReport - the JVM-only jacoco report for the freeRelease variant--uses the class filters you have configured
• createMergedPaidDebugReport - the task you should run when you want to test the paid debug variant
• mergePaidDebugReport - the merging task for the paid debug variant
• jacocoPaidDebugJvmReport - the JVM-only jacoco report for the paidDebug variant--uses the class filters you have configured
• jacocoPaidReleaseJvmReport - the JVM-only jacoco report for the paidRelease variant--uses the class filters you have configured
• createMergedReports - the task you should run when you want to test all variants

(Note that if your project does not have flavors, then the above tasks will be generated with build types only)

android {
    buildTypes {
        debug {
            testCoverageEnabled true
        }
    }
    productFlavors {
        free {
        }
        paid {
        }
    }
}

In order to filter the classes on which Jacoco reports in the merged report, you can also filter by build type and/or product flavor.

mergedReportConfig {
    classFilters {
        // buildType + flavor matches are additive rather than overriding
        debug {
            includes = ['**/com/my/app/base/package/**']
            excludes = [
                    '**/R$*.class',                                 // generated R subclasses
                    '**/R.class',                                   // generated R classes
                    '**/*Test.class',                               // filter test classes
                    '**/BuildConfig*',                              // generated BuildConfig classes

                    '**/*_*.class',                                 // Butterknife/AutoValue/Dagger-generated classes
                    '**/Dagger*.class',                             // Dagger-generated classes
            ]
        }
        free {
            excludes = ["**/App.class"]                             // free flavor debug report additionally filters any class called App
        }
    }
}

Note that the sources included in each report will be the same as the sources for the variant. Therefore, if you have different sources for the free and paid flavors, then make sure to run the appropriate test task.

Finally, in order to to a combined run of local JVM and connected android testing that generates the merged report for the free debug variant,

$ ./gradlew clean createMergedFreeDebugReport

And the same for the paid debug variant"

$ ./gradlew clean createMergedPaidDebugReport

Releases

0.2.0: Runs with Java8 build

• I made a mistake in transitioning 0.1.0 to mavenCentral in that I rebuilt with Java 11 and didn't specify source/target compatibility. 0.2.0 re-enables Java 8 compatibility.

0.1.0: Better Gradle 6+ Support

• It seems some gradle version/jacoco version combos were not picking up the .exec file output. This version changes to specify the output file on a per-test-task basis.
• Note that when I transitioned from bintray to mavenCentral, I accidentally packaged for Java 11. You'll need to upgrade to 0.2.0 if you want your build script to run with a Java8 runtime. If your build already runs on Java 11+, then you're fine with this version.

0.0.3: Gradle 6+ Support

• Gradle 6.0 backtracked on the way that you set additionalSourceDirs and additionalClassDirs, no longer allowing you to use the setters for them. Additionally, I had to change how execution files got added.

0.0.2: Gradle 5+ Support

• Gradle 5.0 enforced that you use additionalSourceDirs and additionalClassDirs in an unfriendly way by throwing a StackOverflowError when you attempted to use the sourceDirectories and classDirectories setters.

0.0.1: Kotlin Support

• Kotlin support (I recommend JaCoCo version 0.8.2 or higher (which I've tested to work with android gradle plugin 3.3.0))
• Creation of JVM-only JaCoCo report tasks for gradle (see above)
• When you run a createMerged<variant name>Report task, HTML and XML for the local JVM report will be included in the output as well.

0.0.0: First release

I used this release myself for a long time, as it worked for my use case (no Kotlin). It works well enough supporting Java code, but it did not provide a built-in JVM-only JaCoCo Report task.