}

    private TestFile writeJavaSourceFile(String className) {
        String sourceFilePath = "src/main/java/${className}.java"
        sourceFilePath = prependRootDirName(sourceFilePath)
        def sourceFile = testDir.file(sourceFilePath)
        sourceFile << "public class $className {}"
        sourceFile
    }

    private TestFile determineClassFile(File sourceFile) {

    TestFile file(String path) {
        projectDir.file(path)
    }

    TestFile groovy(String path) {
        file("src/main/groovy/${sourceFilePath(path)}")
    }

    TestFile java(String path) {
        file("src/main/java/${sourceFilePath(path)}")
    }

    private String sourceFilePath(String path) {
        packageName ? "${packageName.replaceAll("\\.", "/")}/$path" : path
    }

    }

    private static void addPluginSource(TestFile pluginProjectDir, String code) {
        def packageName = "org.gradle.test"
        def sourceFilePath = "${packageName.replaceAll("\\.", "/")}/${"TestPlugin"}.groovy"
        pluginProjectDir.file("src/main/groovy/${sourceFilePath}") << """
            ${packageName ? "package $packageName" : ""}

            class TestPlugin implements $Plugin.name<$Project.name> {