disabling profiling around python-libfaketime example

example.py

# An example to disable profiling when faking time with python-libfaketime.
# Call this once from setup_package or a similar hook at the start of the test run.
# https://github.com/simon-weber/python-libfaketime

def disable_profiling_around_libfaketime(nose_config):
    """
    libfaketime's interception of time system calls will break profilers.

    If we detect that we're running under a profiler, we set up libfaketime callbacks to
    temporarily disable profiling when we're faking the time.
    """

    try:
        import nose_cprofile
    except ImportError:
        return

    profile_plugins = [p for p in nose_config.plugins.plugins if isinstance(p, nose_cprofile.Profile)]
    if not profile_plugins:
        return

    assert len(profile_plugins) == 1
    plugin = profile_plugins[0]
    if plugin.enabled:
        profiler = plugin.prof
        libfaketime.begin_callback = lambda _: profiler.disable()
        libfaketime.end_callback = lambda _: profiler.enable()