'Test the ability to retrieve a ref.'

def test_ref(self):

    cassette_name = self.cassette_name('ref')
    with self.recorder.use_cassette(cassette_name):
        repository = self.gh.repository('sigmavirus24', 'github3.py')
        ref = repository.ref('tags/0.9.3')
    assert isinstance(ref, github3.git.Reference)
