I am trying to write a test for a function that uses async. Can I mix using unittest.TestCase and asyncio.test_utils.TestCase? When I do that, the loop in test_utils.TestCase seems to affect the other code I have. This is a simplified example - $ cat foo.py import asyncio import unittest from asyncio import test_utils async def foo(): return True class Foo1Test(test_utils.TestCase): def setUp(self): super().setUp() self.loop = self.new_test_loop() self.set_event_loop(self.loop) def test_foo(self): res = self.loop.run_until_complete(foo()) assert res is True class Foo2Test(unittest.TestCase): def test_foo(self): loop = asyncio.get_event_loop() res = loop.run_until_complete(foo()) assert res is True $ python3 Python 3.6.1 (default, Apr 4 2017, 09:40:21) [GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.38)] on darwin Type "help", "copyright", "credits" or "license" for more information.

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$ python3 -m unittest foo.py .E ====================================================================== ERROR: test_foo (foo.Foo2Test) ---------------------------------------------------------------------- Traceback (most recent call last): File "/private/tmp/foo.py", line 26, in test_foo loop = asyncio.get_event_loop() File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/events.py", line 678, in get_event_loop return get_event_loop_policy().get_event_loop() File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/events.py", line 584, in get_event_loop % threading.current_thread().name) RuntimeError: There is no current event loop in thread 'MainThread'. ---------------------------------------------------------------------- Ran 2 tests in 0.001s What am I missing? -- Pradip Caulagi http://caulagi.com