[JAVA] Arbitrate the fight between PowerMock and jacoco with Gradle

Overview

Aiming for 100% java UT coverage with a certain PJ When I created a coverage report with jacoco, It will be 0% across the board.

Apparently, jacoco doesn't like powermock, a rough man ... That said, powermock addiction is a death.

Workaround

https://github.com/powermock/powermock/wiki/Code-coverage-with-JaCoCo

Second way to get code coverage with JaCoCo - use offline Instrumentation.

Apparently Offline Instrumentation. There is only an implementation example in Maven and there is not much article on how to write in Gradle, so let's write it.

Dependencies

build.gradle

dependencies {
  testCompile group: 'org.mockito', name: 'mockito-core', version: '2.2.7'
  testCompile group: 'org.powermock', name: 'powermock-api-mockito2', version: '2.0.0-beta.5'
  testCompile group: 'org.powermock', name: 'powermock-module-junit4', version: '2.0.0-beta.5'

  jacoco group: 'org.jacoco', name: 'org.jacoco.ant', version: '0.8.2', classifier: 'nodeps'
  jacocoRuntime group: 'org.jacoco', name: 'org.jacoco.agent', version: '0.8.2', classifier: 'runtime'
}

By the way, please note that Offline Instrumentation works after powermock 1.6.6.

Offline Instrumentation

build.gradle

configurations {
  jacoco
  jacocoRuntime
}

task instrument(dependsOn: ['classes']) {
  ext.outputDir = buildDir.path + '/classes-instrumented'
  doLast {
    ant.taskdef(name: 'instrument',
                classname: 'org.jacoco.ant.InstrumentTask',
                classpath: configurations.jacoco.asPath)
    ant.instrument(destdir: outputDir) {
      fileset(dir: sourceSets.main.output.classesDir)
    }
  }
}

gradle.taskGraph.whenReady { graph ->
  if (graph.hasTask(instrument)) {
    tasks.withType(Test) {
      doFirst {
        systemProperty 'jacoco-agent.destfile', buildDir.path + '/jacoco/jacoco-coverage.exec'
        classpath = files(instrument.outputDir) + classpath + configurations.jacocoRuntime
      }
    }
  }
}

task report(dependsOn: ['instrument', 'test']) {
  doLast {
    ant.taskdef(name: 'report',
                classname: 'org.jacoco.ant.ReportTask',
                classpath: configurations.jacoco.asPath)
    ant.report() {
      executiondata {
        ant.file(file: buildDir.path + '/jacoco/jacoco-coverage.exec')
      }
      structure(name: 'Example') {
         classfiles {
           fileset(dir: sourceSets.main.output.classesDir)
         }
         sourcefiles {
           fileset(dir: 'src/main/java')
         }
      }
      html(destdir: buildDir.path + '/reports/jacoco/test/html')
    }
  }
}

Immediately after compiling, it's an instrument, and it feels like test + jacoco. Now when I try to run the report task,

PowerMock and jacoco have been successfully reconciled.

Impressions

I'm not sure what the instrument is still doing. Actually, it is a multi-project configuration, so I would like to combine coverage reports.

So next time, I will try to combine various documents in a multi-project.