def test_union_int_categorical_with_nan(): ci = CategoricalIndex([1, 2, np.nan]) assert ci.categories.dtype.kind == "i" idx = Index([1, 2]) result = idx.union(ci) expected = Index([1, 2, np.nan], dtype=np.float64) tm.assert_index_equal(result, expected) result = ci.union(idx) tm.assert_index_equal(result, expected)