def test_remove(self): system_commands = [] def fake_system(cmd): system_commands.append(cmd) original_system = os.system os.system = fake_system filenames = ['archive.001.xtm', 'archive.002.xtm', 'archive.003.xtm'] archive = XtmArchive('archive', './path', filenames) archive.remove() self.assertEquals(system_commands, []) os.system = original_system