'When a file is deleted, gen_filenames() no longer returns it.'

def test_deleted_removed(self):

    dirname = tempfile.mkdtemp()
    filename = os.path.join(dirname, 'test_deleted_removed_module.py')
    self.addCleanup(shutil.rmtree, dirname)
    with open(filename, 'w'):
        pass
    with extend_sys_path(dirname):
        import_module('test_deleted_removed_module')
    self.assertFileFound(filename)
    os.unlink(filename)
    self.assertFileNotFound(filename)
