Can you use self.assertRaises as an async context manager?

I'd like to test that a python 3 coro fails with a particular exception, but this functionality doesn't seem to be implemented.

async with self.assertRaises(TestExceptionType):
    await my_func()

as the unit test fails like this:

...
File "/Users/...../tests.py", line 144, in go
    async with self.assertRaises(TestExceptionType):
AttributeError: __aexit__

So my question is: should this work? And if not, what's the best way to assert a failing async function?