human
Here's a good function header given the following:
I wrote the below code

    class MockCache(object, ):
        def store(self, copyCmd, relativeDst):
            pass
        def fetcher(self, targetPath, digest, **kwargs):
            return MockCacheFetcher()
    class MockCacheFetcher(object, ):
        def set_stage(self, stage):
            pass
        def fetch(self):
            raise FetchError('Mock    cache    always    fails    for    tests')
        def __str__(self):
            return '[mock    fetch    cache]'
    monkeypatch.setattr(spack, 'fetch_cache', MockCache())

What's a good function header?
assistant
#Here's a good function header.

@pytest.fixture(autouse=True)
def mock_fetch_cache(monkeypatch):