then:
        project.idea.module.excludeDirs == [project.buildDir, project.file('.gradle')] as Set
    }

    def "adds 'cleanIdea' task to projects"() {
        when:
        applyPluginToProjects()

        then:
        project.cleanIdea instanceof Task
        childProject.cleanIdea instanceof Task
    }

     def "adds single entry libraries from source sets"() {
        when:

defaultTasks 'idea', 'cleanIdea'

allprojects {
    apply plugin: 'idea'
}

idea.project.jdkName = '1.6'
idea.project.languageLevel = '1.6'

subprojects {
    apply plugin: 'java-library'

    idea {
        module {
            downloadJavadoc = true
        }
    }

    repositories {
        mavenCentral()
    }

    dependencies {
        testImplementation 'junit:junit:4.7'
    }

dependencies {
    runtimeOnly 'commons-collections:commons-collections:3.2.2@jar'
}

cleanIdea.doLast {
    assert !file("api/api.iml").isFile()

dependencies {
    providedCompile 'org.slf4j:slf4j-api:1.5.8@jar'
    api project(':api'), files("$projectDir/lib/compile-1.0.jar")
    runtimeOnly "commons-lang:commons-lang:2.4"
    runtimeOnly "commons-io:commons-io:1.2"
}

cleanIdea.doLast {
    assert !file("webservice/webservice.iml").isFile()

==== Disabling merging with a complete overwrite

To completely rewrite existing IDEA files, execute a clean task together with its corresponding generation task, like “`gradle cleanIdea idea`” (in that order). If you want to make this the default behavior, add “`tasks.idea.dependsOn(cleanIdea)`” to your build script. This makes it unnecessary to execute the clean task explicitly.

        assert getFile(project: 'shared/api', "shared-api.iml").exists()
        assert getFile(project: 'contrib', "cool-contrib.iml").exists()

        //when
        executer.withTasks("cleanIdea").run()

        //then
        assert !getFile(project: 'shared/api', "shared-api.iml").exists()
        assert !getFile(project: 'contrib', "cool-contrib.iml").exists()
    }

    @Test

        assertHasExpectedContents('root.iml')
        assertHasExpectedContents('api/api.iml')
        assertHasExpectedContents('webservice/webservice.iml')

        executer.withTasks('cleanIdea').run()
    }

    @Test
    @ToBeFixedForConfigurationCache
    void worksWithAnEmptyProject() {
        executer.withTasks('idea').run()

        assertHasExpectedContents('root.ipr')