func buildProg(t *testing.T, prog string, dir string, tag string, flags []string) (string, string) {
	// Create subdirs.
	subdir := filepath.Join(dir, prog+"dir"+tag)
	if err := os.Mkdir(subdir, 0777); err != nil {
		t.Fatalf("can't create outdir %s: %v", subdir, err)
	}
	depdir := filepath.Join(subdir, "dep")
	if err := os.Mkdir(depdir, 0777); err != nil {
		t.Fatalf("can't create outdir %s: %v", depdir, err)
	}

	readZip       func(rev, subdir, remote, target string) []string                                   // cmd to read rev's subdir as zip file
	doReadZip     func(ctx context.Context, dst io.Writer, workDir, rev, subdir, remote string) error // arbitrary function to read rev's subdir as zip file
}

var re = lazyregexp.New

var vcsCmds = map[string]*vcsCmd{
	"hg": {

			},
		},

		{
			repo:   gitrepo1,
			rev:    "aaaaaaaaab",
			subdir: "",
			err:    "unknown revision",
		},
		{
			repo:   hgrepo1,
			rev:    "aaaaaaaaab",
			subdir: "",
			err:    "unknown revision",
		},

		{
			repo:   vgotest1,
			rev:    "submod/v1.0.4",
			subdir: "submod",
			files: map[string]uint64{
				"prefix/":                0,

                outputDirectory = file("build/output")
            }
        """
        def toBeModifiedPath = "in/some/subdir/input1.txt"
        def toBeRemovedPath = "in/some/subdir/input2.txt"
        def toBeAddedPath = "in/some/other/subdir/other-input.txt"
        file("input/$toBeModifiedPath").text = "input to copy"
        file("input/${toBeRemovedPath}").text = "input to copy"

        when:

			// We need to check that info is not nil. This may happen when the incoming err is not nil due to stale mounts or permission errors.
			if info != nil && info.IsDir() {
				// skip subdirs of the volume: it only matters the first level to unmount, otherwise it would try to unmount subdir of the volume
				return filepath.SkipDir
			}

			return nil
		})
		if err != nil {
			return fmt.Errorf("error processing %s: %s", fullContainerDirPath, err)

    private GradleVersion determineGradleVersionFromBuildReceipt(File checksumDir) throws Exception {
        List<File> subDirs = listDirs(checksumDir);
        Preconditions.checkArgument(subDirs.size() == 1, "A Gradle distribution must contain exactly one subdirectory: %s", subDirs);
        return determineGradleVersionFromDistribution(single(subDirs));
    }

    @VisibleForTesting

            }
        '''.stripIndent()

        when:
        run 'sync'

        then:
        file('dest').assertHasDescendants(
            'dir1/file1.txt',
            'dir2/subdir/file2.txt',
            'dir2/file3.txt',
            'emptyDir'
        )
    }

    def 'preserve keeps specified files in destDir'() {
        given:
        defaultSourceFileTree()

             */
            if (Files.isDirectory(file)) {
                Map<Path, String> names = new HashMap<>();
                try (Stream<Path> subdirs = Files.list(file)) {
                    subdirs.filter(Files::isDirectory).forEach((subdir) -> {
                        Path mf = subdir.resolve(MODULE_INFO);
                        if (Files.isRegularFile(mf)) {
                            String name = null;

    public File getStubDir() {
        return stubDir;
    }

    /**
     * Sets the directory where Java stubs for Groovy classes will be stored during Java/Groovy joint
     * compilation. Defaults to {@code null}, in which case a temporary directory will be used.
     */
    public void setStubDir(File stubDir) {
        this.stubDir = stubDir;
    }

    /**

        def destinationDir = spec.getDestinationDir()
        createNewFile(new File(destinationDir, "file.txt"))
        createNewFile(new File(destinationDir, "subDir/another-file.txt"))
        createNewFile(new File(destinationDir, "subDir/some-dest-file.class"))
        def annotationOutput = createNewDirectory(file("annotationOut"))
        createNewFile(new File(annotationOutput, "some-ann-file.ann"))