def test_add_index(self):
        fs = FieldSelector(["foo", "bar"])
        self.assertEqual(fs.selectors, ["foo", "bar"])

        fs.add_index(0)
        self.assertEqual(fs.selectors, ["foo", "bar", 0])

        with self.assertRaisesRegexp(ValueError,
                                     "index must be an int or a long"):
            fs.add_index(0.0)

        self.assertEqual(fs.selectors, ["foo", "bar", 0])
    def test_add_index(self):
        fs = FieldSelector(["foo", "bar"])
        self.assertEqual(fs.selectors, ["foo", "bar"])

        fs.add_index(0)
        self.assertEqual(fs.selectors, ["foo", "bar", 0])

        with self.assertRaisesRegexp(
            ValueError, "index must be an int or a long"
        ):
            fs.add_index(0.0)

        self.assertEqual(fs.selectors, ["foo", "bar", 0])