@Test
public void testGetSubDirs() {

    String dir = TestData.getTemporaryTestDir();
    Set<String> subdirs = Sets.newHashSet();
    for (int i = 0; i < TestData.getScaleCount(); i++) {
        String subdir = TestData.getString();
        FileSystem.mkdirs(FileSystem.makePath(dir, subdir));
        subdirs.add(subdir);
    }
    Assert.assertEquals(subdirs, FileSystem.getSubDirs(dir));
}