How to ignore generated Kotlin files in Jacoco?

I am using

• build.gradle.kts
• Jacoco: id(“org.barfuin.gradle.jacocolog”) version “3.1.0”
• Optics from Arrow library

Arrow library generates __OpticsKt files that don’t have coverage in Jacoco. How to ignore them in the build.gradle.kts?

Answer

You need to add tasks.jacocoTestReport { block:

tasks.jacocoTestReport {
  classDirectories.setFrom(
    sourceSets.main.get().output.asFileTree.matching {
      exclude("**/*__Optics*.class")
    },
  )
}

How does it work?

It seems like Jacoco uses .class files to generate coverage. Check in your build folder for these files.

Here, you can see we have the .class file, that we can exclude in the jacocoTestReport block with the correct glob format.