copying comment from @graingert

(please make all comments on the code so that there can be a thread and Resolve button)

can you test with eager tasks as well as regular tasks?

I think something like this:

class TestTaskGroupLazy(IsolatedAsyncioTestCase):
    loop_factory = asyncio.EventLoop


class TestTaskGroupEager(TestTaskGroupLazy):
    @staticmethod
    def loop_factory():
        loop = asyncio.EventLoop()
        loop.set_task_factory(asyncio.eager_task_factory)
        return loop

if you find the existing tests fail in eager tasks then probably just add the eager tests for your newly added tests.