'Fixture providing a mock for utils.read_file for git-commit-id.
On fixture teardown, it makes sure it got called with git-commit-id as
argument.'

@pytest.fixture
def commit_file_mock(self, mocker):

    mocker.patch('qutebrowser.utils.version.subprocess', side_effect=AssertionError)
    m = mocker.patch('qutebrowser.utils.version.utils.read_file')
    (yield m)
    m.assert_called_with('git-commit-id')
