def test_containsExtension(self):
d = Directory("dir")
f1 = File("dir/text.txt")
f2 = File("dir/image.png")
d.createDir()
f1.createFile()
f2.createFile()
self.assertTrue(d.containsFileExtension(".txt"), "Directory contains .txt")
self.assertTrue(d.containsFileExtension(".png"), "Directory contains .png")
self.assertFalse(d.containsFileExtension(".pdf"), "Directory does not contain .pdf")
d.removeDir()
