Ability to check current frozen time configuration

[plaa]

It would be useful if test code could check the current frozen time configuration (e.g. is time currently frozen, what packages are ignored, is real_asyncio set or not). Currently it can only be done by introspecting internal details.

For example, I just implemented a assert_with_retry helper function which waits for a condition to become true (when a background asyncio task is performing some operation). It took me a long time to realize freeze_time was causing asyncio.sleep to lock up, causing tests to freeze up. I wanted to avoid the pain from other developers, so I started looking at how can I detect frozen time without real_asyncio=True option. I ended up writing the functions below (which are way less than ideal) and having assert_with_retry raise an exception with clear instructions in case it was called with frozen time without real_asyncio. It would have been great to have a stable API from which to check them.

import asyncio
import freezegun


def is_time_frozen() -> bool:
    """Check whether time is currently frozen."""
    return len(freezegun.api.freeze_factories) > 0


_cached_event_loop_class: type[asyncio.AbstractEventLoop] | None = None


def is_time_frozen_with_real_asyncio() -> bool:
    global _cached_event_loop_class  # noqa: PLW0603
    if _cached_event_loop_class is None:
        event_loop = asyncio.new_event_loop()
        event_loop.close()
        _cached_event_loop_class = type(event_loop)
    s = repr(_cached_event_loop_class.time)
    # Freezegun sets the event loop .time method to a lambda function which uses
    # the real tick method. This is detected based on the method name "freeze_time"
    # being in the function repr. The file test_freezegun_helper.py includes tests
    # so this does not break during a library upgrade.
    return "freeze_time" in s