def METHOD_NAME(self):
    t1 = os.path.join(FIXTURES_DIR, 'c_t1.csv')
    t2 = os.path.join(FIXTURES_DIR, 'c_t2.csv')
    runner = CliRunner()
    diffed = runner.invoke(diff, [t1, t2, '--group-by', 'id'])
    assert 0 == diffed.exit_code
    assert 'values_changed' in diffed.output
    assert '"new_value": "Chicken"' in diffed.output