Filter JaCoCo coverage reports with Gradle

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/**')
        }))
    }
}