def test_tag_exists_fails(self):
        self.repo.create_tag('0.3.0')
        self.assertRaises(
            TagExists,
            self.calculate_base_branch, '0.3.0')
Some pure python tests...
dataset/ETHPy150Open ClusterHQ/flocker/admin/test/test_release.py/CalculateBaseBranchTests.test_tag_exists_fails--crossover with--dataset/ETHPy150Open ipython/ipython-py3k/IPython/testing/plugin/simple.py/pyfunc