Filter JaCoCo coverage reports with Gradle

Question

Thanks to, Yannick Welsch:

After searching Google, reading the Gradle docs and going through older StackOverflow posts, I found this answer on the Official gradle forums!

jacocoTestReport {
    afterEvaluate {
        classDirectories.setFrom(files(classDirectories.files.collect {
            fileTree(dir: it, exclude: 'com/blah/**')
        }))
    }
}

Source: https://issues.gradle.org/browse/GRADLE-2955

For older gradle versions < 5.x may need to use classDirectories = files(classDirectories.files.collect { instead of classDirectories.setFrom

Solution to my build.gradle for Java/Groovy projects:

apply plugin: 'java'
apply plugin: 'jacoco'

jacocoTestReport {
    reports {
        xml {
            enabled true // coveralls plugin depends on xml format report
        }

        html {
            enabled true
        }
    }

    afterEvaluate {
        classDirectories = files(classDirectories.files.collect {
            fileTree(dir: it,
                    exclude: ['codeeval/**',
                              'crackingthecode/part3knowledgebased/**',
                              '**/Chapter7ObjectOrientedDesign**',
                              '**/Chapter11Testing**',
                              '**/Chapter12SystemDesignAndMemoryLimits**',
                              'projecteuler/**'])
        })
    }
}

As you can see, I was successfully able to add more to exclude: in order to filter a few packages.

Source: https://github.com/jaredsburrows/CS-Interview-Questions/blob/master/build.gradle

Custom tasks for other projects such as Android:

apply plugin: 'jacoco'

task jacocoReport(type: JacocoReport) {
    reports {
        xml {
            enabled true // coveralls plugin depends on xml format report
        }

        html {
            enabled true
        }
    }

    afterEvaluate {
        classDirectories = files(classDirectories.files.collect {
            fileTree(dir: it,
                    exclude: ['codeeval/**',
                              'crackingthecode/part3knowledgebased/**',
                              '**/Chapter7ObjectOrientedDesign**',
                              '**/Chapter11Testing**',
                              '**/Chapter12SystemDesignAndMemoryLimits**',
                              'projecteuler/**'])
        })
    }
}

Source: https://github.com/jaredsburrows/android-gradle-java-app-template/blob/master/gradle/quality.gradle#L59

For Gradle version 5.x, the classDirectories = files(...) gives a deprecation warning and does not work at all starting from Gradle 6.0 This is the nondeprecated way of excluding classes:

jacocoTestReport {
    afterEvaluate {
        classDirectories.setFrom(files(classDirectories.files.collect {
            fileTree(dir: it, exclude: 'com/exclude/**')
        }))
    }
}

for me, it's fine working with

test {
  jacoco {
    excludes += ['codeeval/**',
                 'crackingthecode/part3knowledgebased/**',
                 '**/Chapter7ObjectOrientedDesign**',
                 '**/Chapter11Testing**',
                 '**/Chapter12SystemDesignAndMemoryLimits**',
                 'projecteuler/**']
  }
}

as stated out in documentation https://docs.gradle.org/current/userguide/jacoco_plugin.html#N16E62 and initally asked so the answer is:

so if you ask me: it's not a question of

excludes = ["projecteuler/**"]

or

excludes += ["projecteuler/**"]

but

excludes = ["**/projecteuler/**"]

to exclude a package *.projecteuler.*

and test {} on project level, not nested in jacocoTestReport

For Gradle6 Use something like below, because they made classDirectories as final, we cannot re-assign it, but a setter method exists classDirectories.setFrom which can be utilized

    jacocoTestReport {
    reports {
        xml.enabled true
        html.enabled true
        html.destination file("$buildDir/reports/jacoco")
    }

    afterEvaluate {
        classDirectories.setFrom(files(classDirectories.files.collect {
            fileTree(dir: it,
                    exclude: ['**/server/**',
                              '**/model/**',
                              '**/command/**'
                    ]
            )
        }))
    }
}

In order to filter in jacoco report, exclusion need to be done in two task jacocoTestReport and jacocoTestCoverageVerification.

sample code

    def jacocoExclude = ['**/example/**', '**/*Module*.class']

    jacocoTestReport {
        afterEvaluate {
            getClassDirectories().setFrom(classDirectories.files.collect {
                fileTree(dir: it, exclude: jacocoExclude)
            })
        }
    }

    jacocoTestCoverageVerification {
        afterEvaluate {
            getClassDirectories().setFrom(classDirectories.files.collect {
                fileTree(dir: it, exclude: jacocoExclude)
            })
        }

        ...
    }