Using private function with unittest.assertRaises()

unittest_snippet.py

class SomeTest(unittest.TestCase):

    .
    .
    .

    def test_queue(self):
        
        .
        .
        .

        def check_finished_tasks():
            for task_id in ids:
                self.task_queue.get_result(task_id)

        self.assertRaises(KeyError, check_finished_tasks)
        
        .
        .
        .