Jacoco & Gradle Test Kit with Java

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It is still true that using withDebug(true) would work to get coverage as the tests are run in-process, but it is also true that you can then for example not use withEnvironment.

I actually set this up some days ago to work properly without needing to do withDebug.

I basically do something very similar to what the plugin linked in OP here is doing, I just didn’t like too much how it is done there and had needed infrastructure already anyway, that is a base class for the functional tests that prepares a base build I extend in the individual tests, so was able to just write the gradle.properties there as needed.

I

  • create a resolvable configuration jacocoAgentJar
  • add as dependency org.jacoco:org.jacoco.agent:...:runtime
  • set jacocoAgentJar.singleFile.absolutePath as the value of a system property for the test task
  • set the<JacocoTaskExtension>().destinationFile!!.absolutePath as the value of another system property for the test task
  • add a doLast { ... } action to the test task that gets the read lock on the JaCoCo result file to wait for the test having written to it like
    doLast {
    // wait for the read lock on the file, otherwise the daemon might still
    // have the write lock and Gradle complains that it cannot snapshot
    // the file as output of this task and as input of the report task
    FileChannel.open(jacocoDestfile.toPath(), READ).use {
        it.lock(0, Long.MAX_VALUE, true).release()
    }
}
  • and in the base class for the tests I prepare the gradle.properties file with
    def jacocoAgentJar = System.getProperty('jacocoAgentJar').replace($/\/$, $/\\/$)
def jacocoDestfile = System.getProperty('jacocoDestfile').replace($/\/$, $/\\/$)
    and writing to the file
    org.gradle.jvmargs = -javaagent:$jacocoAgentJar=destfile=$jacocoDestfile

This seems to work fine so far.

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