chore: missing tests for Index[Any]

Author: cmp0xff

tests/indexes/arithmetic/test_add.py

@@ -1,16 +1,23 @@
 import numpy as np
 from numpy import typing as npt  # noqa: F401
 import pandas as pd
-from typing_extensions import assert_type
+from typing_extensions import (
+    Never,
+    assert_type,
+)
 
-from tests import check
+from tests import (
+    TYPE_CHECKING_INVALID_USAGE,
+    check,
+)
 
-# left operand
+# left operands
 left_i = pd.MultiIndex.from_tuples([(1,), (2,), (3,)]).levels[0]
+left_str = pd.MultiIndex.from_tuples([("1",), ("2",), ("3_",)]).levels[0]
 
 
-def test_add_py_scalar() -> None:
-    """Test pd.Index[Any] + Python native scalars"""
+def test_add_i_py_scalar() -> None:
+    """Test pd.Index[Any] (int) + Python native scalars"""
     b, i, f, c = True, 1, 1.0, 1j
 
     check(assert_type(left_i + b, pd.Index), pd.Index)
@@ -24,8 +31,8 @@ def test_add_py_scalar() -> None:
     check(assert_type(c + left_i, pd.Index), pd.Index)
 
 
-def test_add_py_sequence() -> None:
-    """Test pd.Index[Any] + Python native sequence"""
+def test_add_i_py_sequence() -> None:
+    """Test pd.Index[Any] (int) + Python native sequence"""
     b, i, f, c = [True, False, True], [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
 
     check(assert_type(left_i + b, pd.Index), pd.Index)
@@ -39,8 +46,8 @@ def test_add_py_sequence() -> None:
     check(assert_type(c + left_i, pd.Index), pd.Index)
 
 
-def test_add_numpy_array() -> None:
-    """Test pd.Index[Any] + numpy array"""
+def test_add_i_numpy_array() -> None:
+    """Test pd.Index[Any] (int) + numpy array"""
     b = np.array([True, False, True], np.bool_)
     i = np.array([2, 3, 5], np.int64)
     f = np.array([1.0, 2.0, 3.0], np.float64)
@@ -53,7 +60,7 @@ def test_add_numpy_array() -> None:
 
     # `numpy` typing gives the corresponding `ndarray`s in the static type
     # checking, where our `__radd__` cannot override. At runtime, they return
-    # `Series`s.
+    # `Index`s.
     # `mypy` thinks the return types are `Any`, which is a bug.
     check(
         assert_type(b + left_i, "npt.NDArray[np.bool_]"), pd.Index  # type: ignore[assert-type]
@@ -69,19 +76,31 @@ def test_add_numpy_array() -> None:
     )
 
 
-def test_add_pd_series() -> None:
-    """Test pd.Index[Any] + pandas index"""
+def test_add_i_pd_series() -> None:
+    """Test pd.Index[Any] (int) + pandas index"""
+    a = pd.MultiIndex.from_tuples([(1,), (2,), (3,)]).levels[0]
     b = pd.Index([True, False, True])
     i = pd.Index([2, 3, 5])
     f = pd.Index([1.0, 2.0, 3.0])
     c = pd.Index([1.1j, 2.2j, 4.1j])
 
+    check(assert_type(left_i + a, pd.Index), pd.Index)
     check(assert_type(left_i + b, pd.Index), pd.Index)
     check(assert_type(left_i + i, pd.Index), pd.Index)
     check(assert_type(left_i + f, pd.Index), pd.Index)
     check(assert_type(left_i + c, pd.Index), pd.Index)
 
+    check(assert_type(a + left_i, pd.Index), pd.Index)
     check(assert_type(b + left_i, pd.Index), pd.Index)
     check(assert_type(i + left_i, pd.Index), pd.Index)
     check(assert_type(f + left_i, pd.Index), pd.Index)
     check(assert_type(c + left_i, pd.Index), pd.Index)
+
+
+def test_add_i_py_str() -> None:
+    """Test pd.Index[Any] (int) + Python str"""
+    s = "abc"
+
+    if TYPE_CHECKING_INVALID_USAGE:
+        assert_type(left_i + s, Never)
+        assert_type(s + left_i, Never)