jacoco在android studio 上的配置使用（2021版）

经过多次测试，参考国内外诸多资料。现整理配置如下。
环境：
classpath “com.android.tools.build:gradle:7.0.2”
ext.kotlin_version = ‘1.6.0’

//jacoco.gradle
import org.gradle.api.internal.project.ProjectInternal

apply plugin: 'jacoco'

jacoco {
    toolVersion = "0.8.7"
}

android {
    buildTypes {
        debug {
            testCoverageEnabled = true
        }
    }
}


project.apply {
    project.extensions.create("jacocoAndroidUnitTestReport",
            JacocoAndroidUnitTestReportExtension,
            JacocoAndroidUnitTestReportExtension.defaultExcludesFactory())
    project.plugins.apply(JacocoPlugin)
    Plugin plugin = findAndroidPluginOrThrow(project.plugins)

    def variants = getVariants(project, plugin)
    Task jacocoTestReportTask = findOrCreateJacocoTestReportTask(project.tasks)

    variants.all { variant ->
        def sourceDirs = variant.sourceSets.java.srcDirs.collect { it.path }.flatten()
        def classesDir
        if (variant.hasProperty('javaCompileProvider')) {
            classesDir = variant.javaCompileProvider.get().destinationDir
        } else {
            classesDir = variant.javaCompile.destinationDir
        }
        def unitTestTask = tasks.getByName("test${variant.name.capitalize()}UnitTest")
        def checkTask = tasks.getByName("connectedCheck")

        def androidTestPath = "../app/build/outputs/code_coverage/debugAndroidTest/connected/"

        def executionData = unitTestTask.jacoco.destinationFile.path

        FileTree javaTree = project.fileTree(dir: classesDir, excludes: project.jacocoAndroidUnitTestReport.excludes)
        def kotlinClassesDir = "${project.buildDir}/tmp/kotlin-classes/${variant.name}"
        def kotlinTree =
                project.fileTree(dir: kotlinClassesDir, excludes: project.jacocoAndroidUnitTestReport.excludes)

        JacocoReport reportTask = project.tasks.create("jacoco${unitTestTask.name.capitalize()}Report",
                JacocoReport)

        reportTask.dependsOn unitTestTask
        reportTask.dependsOn checkTask

        reportTask.group = "Reporting"
        reportTask.executionData.setFrom(project.fileTree(executionData) + project.fileTree(androidTestPath))
        reportTask.sourceDirectories.setFrom(project.files(sourceDirs))
        reportTask.classDirectories.setFrom(javaTree + kotlinTree)

        reportTask.reports {
            def destination = project.jacocoAndroidUnitTestReport.destination

            xml.enabled = true
            html.enabled true
            html.destination new File((destination == null) ? "${project.buildDir}/jacoco/jacocoHtml" : "${destination.trim()}/jacocoHtml")
        }
        jacocoTestReportTask.dependsOn reportTask
    }
}

class JacocoAndroidUnitTestReportExtension {

    public static final Collection<String> androidDataBindingExcludes =
            ['android/databinding/**/*.class',
             '**/android/databinding/*Binding.class',
             '**/databinding/*Binding.class',
             '**/databinding/*BindingImpl.class',
             '**/databinding/*Sw600dpImpl.class',
             '**/BR.*'].asImmutable()

    public static final Collection<String> androidExcludes =
            ['**/R.class',
             '**/R$*.class',
             '**/BuildConfig.*',
             '**/Manifest*.*'].asImmutable()

    public static final Collection<String> butterKnifeExcludes =
            ['**/*$ViewInjector*.*',
             '**/*$ViewBinder*.*'].asImmutable()

    public static final Collection<String> dagger2Excludes =
            ['**/*_MembersInjector.class',
             '**/Dagger*Component.class',
             '**/Dagger*Component$Builder.class',
             '**/*Module_*Factory.class'].asImmutable()

    public static final Collection<String> defaultExcludes =
            (androidDataBindingExcludes + androidExcludes + butterKnifeExcludes + dagger2Excludes)
                    .asImmutable()

    def static defaultExcludesFactory = { defaultExcludes }

    Collection<String> excludes
    boolean csv
    boolean html
    boolean xml
    String destination

    JacocoAndroidUnitTestReportExtension(Collection<String> excludes) {
        this.excludes = excludes
        this.csv = true
        this.html = true
        this.xml = true
        this.destination = null
    }
}


private static def getVariants(ProjectInternal project, Plugin plugin) {
    boolean isLibraryPlugin = plugin.class.name.endsWith('.LibraryPlugin')
    project.android[isLibraryPlugin ? "libraryVariants" : "applicationVariants"]
}

private static Plugin findAndroidPluginOrThrow(PluginContainer plugins) {
    Plugin plugin = plugins.findPlugin('android') ?: plugins.findPlugin('android-library')
    if (!plugin) {
        throw new GradleException(
                'You must apply the Android plugin or the Android library plugin before using the jacoco-android plugin')
    }
    plugin
}

private static Task findOrCreateJacocoTestReportTask(TaskContainer tasks) {
    Task jacocoTestReportTask = tasks.findByName("jacocoTestReport")
    if (!jacocoTestReportTask) {
        jacocoTestReportTask = tasks.create("jacocoTestReport")
        jacocoTestReportTask.group = "Reporting"
    }
    jacocoTestReportTask
}

使用方式：
在需要的项目的build.gradle 中配置apply from: "jacoco.gradle"即可。
打开右侧gradle侧边栏，点击reporting中的jacocoTestReport任务。
等待完成在build/jacoco/打开index.html即可

有效参考：
插件式配置,缺点是缺少对AndroidTest目录的配置。

踩坑日记之Gradle自定义JacocoReport跟Test task，缺点是只对java项目有效。

注意：
JaCoCo与PowerMock是不兼容的,覆盖率为0。
https://github.com/powermock/powermock/wiki/Code-coverage-with-JaCoCo