def test_exception(self, exc, mocker, tmpdir):
        """Test with subprocess.check_output raising an exception.

        Args:
            exc: The exception to raise.
        """
        m = mocker.patch("qutebrowser.utils.version.os")
        m.path.isdir.return_value = True
        mocker.patch("qutebrowser.utils.version.subprocess.check_output", side_effect=exc)
        ret = version._git_str_subprocess(str(tmpdir))
        assert ret is None

 def test_missing_dir(self, tmpdir):
     """Test with a directory which doesn't exist."""
     ret = version._git_str_subprocess(str(tmpdir / 'does-not-exist'))
     assert ret is None

 def test_real_git(self, git_repo):
     """Test with a real git repository."""
     ret = version._git_str_subprocess(str(git_repo))
     assert ret == 'foobar (1970-01-01 01:00:00 +0100)'