title: Python unittest + asyncio hangs forever
body: <p>Why does the following test hang forever?</p>
  
  <pre><code>import asyncio
  import unittest
  
  
  class TestCancellation(unittest.IsolatedAsyncioTestCase):
  
      async def test_works(self):
          task = asyncio.create_task(asyncio.sleep(5))
          await asyncio.sleep(2)
          task.cancel()
          await task
  
  
  if __name__ == '__main__':
      unittest.main()
  </code></pre>