@Test
public void testDeleteQuietly() throws Exception {

	// should ignore the call
	FileUtils.deleteDirectoryQuietly(null);
	File doesNotExist = new File(tmp.getRoot(), "abc");
	FileUtils.deleteDirectoryQuietly(doesNotExist);
	File cannotDeleteParent = tmp.newFolder();
	File cannotDeleteChild = new File(cannotDeleteParent, "child");
	try {
		assumeTrue(cannotDeleteChild.createNewFile());
		assumeTrue(cannotDeleteParent.setWritable(false));
		assumeTrue(cannotDeleteChild.setWritable(false));
		FileUtils.deleteDirectoryQuietly(cannotDeleteParent);
	}
	finally {
		//noinspection ResultOfMethodCallIgnored
		cannotDeleteParent.setWritable(true);
		//noinspection ResultOfMethodCallIgnored
		cannotDeleteChild.setWritable(true);
	}
}