### Question:
UtilFolder { public static boolean isDirectory(String path) { return path != null && new File(path).isDirectory(); } private  UtilFolder(); static List<File> getDirectories(File path); static String getPath(String... path); static String getPathSeparator(String separator, String... path); static void deleteDirectory(File element); static boolean isDirectory(String path);  }### Answer:
@Test void testIsDirectory() throws IOException { assertFalse(UtilFolder.isDirectory(null)); final Path dir = Files.createTempDirectory("temp"); assertTrue(UtilFolder.isDirectory(dir.toFile().getPath())); Files.delete(dir); assertFalse(UtilFolder.isDirectory(dir.toFile().getPath())); }