1. build.gradle

在项目的 build.gradle 中引入 jacoco core 依赖：

apply plugin: 'maven'

buildscript {
    repositories {
        jcenter()
        google()
        maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.3'
        classpath "org.jacoco:org.jacoco.core:0.8.5"
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

2. 新建 jacoco-report.gradle

在项目根目录新建一个 jacoco-report.gradle 文件，其中主要定义了一个 Gradle 任务：jacocoCoverageTestReport。如下：

apply plugin: 'jacoco'

tasks.withType(Test) {
    jacoco.includeNoLocationClasses = true
}

ext {
    getFileFilter = { ->
        def jacocoSkipClasses = null
        if (project.hasProperty('jacocoSkipClasses')) {
            jacocoSkipClasses = project.property('jacocoSkipClasses')
        }

        def fileFilter = ['**/R.class', '**/R$*.class', '**/BuildConfig.*', '**/Manifest*.*', '**/*Test*.*', 'android/**/*.*']
        if (jacocoSkipClasses != null) {
            fileFilter.addAll(jacocoSkipClasses)
        }

        return fileFilter
    }
}

/**
 * buildTypes {
 *     debug {
 *         minifyEnabled false
 *     }
 *     coverageDebug {
 *         minifyEnabled false
 *         testCoverageEnabled true
 *     }
 * }
 */
task jacocoCoverageTestReport(type: JacocoReport, dependsOn: ['testCoverageDebugUnitTest', 'createCoverageDebugCoverageReport']) {
    reports {
        xml.enabled = true
        html.enabled = true
    }

    def fileFilter = project.getFileFilter()
    def coverageDebugTree = fileTree(dir: "$project.buildDir/intermediates/classes/coverageDebug", excludes: fileFilter)
    def coverageDebugTreeNewGradle = fileTree(dir: "$project.buildDir/intermediates/javac/coverageDebug/classes", excludes: fileFilter)
    def mainSrc = "$project.projectDir/src/main/java"

    sourceDirectories = files([mainSrc])
    classDirectories = files([coverageDebugTree, coverageDebugTreeNewGradle])
    executionData = fileTree(dir: project.buildDir, includes: [
            'jacoco/testCoverageDebugUnitTest.exec', 'outputs/code-coverage/connected/*coverage.ec'
    ])
}

3. app/build.gradle

在 SDK/App module 对应的 build.gradle 中进行 jacoco 任务配置：

• 引入 jacoco-report.gradle；
• 添加 coverageDebug BuildType。

如下：

apply plugin: 'com.android.library'
apply from: '../jacoco-report.gradle'


android {
    compileSdkVersion 28
    buildToolsVersion "29.0.1"

    defaultConfig {
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        debug {
            minifyEnabled false
        }
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), '../proguard-rules.pro'
        }
        coverageDebug {
            minifyEnabled false
            testCoverageEnabled true
        }
    }

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

        unitTests.returnDefaultValues = true
    }

    lintOptions {
        abortOnError false
    }
}


dependencies {
    // ...
    // other dependencies
    
    // for test.
    testImplementation 'junit:junit:4.12'

    // power mockito
    testImplementation 'org.mockito:mockito-core:2.8.9'
    testImplementation "org.powermock:powermock-api-mockito2:1.7.4"
    testImplementation "org.powermock:powermock-module-junit4:1.7.4"
    testImplementation "org.powermock:powermock-module-junit4-rule:1.7.4"
    testImplementation "org.powermock:powermock-classloading-xstream:1.7.4"
}

3. 编写对应的测试用例

在对应 module 的 src/test/ 目录下编写对应的代码测试用例。

4. 运行 jacocoCoverageTestReport

Run Task jacocoCoverageTestReport

在 Android Studio 的 Gradle 任务窗格中，找到 project/module/Tasks/other/jacocoCoverageTestReport 这个任务，双击运行，即可生成代码行覆盖率报告。

5. 查看报告

打开 project/module/build/reports/jacoco/jacocoCoverageTestReport/html/index.html 文件，即可查看各个代码文件的行覆盖率。

Report HTML file path

覆盖率报告 HTML 打开后一般如下：

Report