TST: Add regression tests for setitem with different string storage (…

pandas/tests/strings/test_strings.py

@@ -818,3 +818,33 @@ def test_decode_with_dtype_none():
         result = ser.str.decode("utf-8", dtype=None)
         expected = Series(["a", "b", "c"], dtype="str")
         tm.assert_series_equal(result, expected)
+
+
+def test_setitem_with_different_string_storage():
+    # GH#52987
+    # Test setitem with values from different string storage type
+    pytest.importorskip("pyarrow")
+
+    # Test Series[string[python]].__setitem__(Series[string[pyarrow]])
+    ser_python = Series(range(5), dtype="string[python]")
+    ser_pyarrow = ser_python.astype("string[pyarrow]")
+
+    ser_python[:2] = ser_pyarrow[:2]
+    expected = Series(["0", "1", "2", "3", "4"], dtype="string[python]")
+    tm.assert_series_equal(ser_python, expected)
+
+    # Test Series[string[pyarrow]].__setitem__(Series[string[python]])
+    ser_pyarrow = Series(range(5), dtype="string[pyarrow]")
+    ser_python = ser_pyarrow.astype("string[python]")
+
+    ser_pyarrow[:2] = ser_python[:2]
+    expected = Series(["0", "1", "2", "3", "4"], dtype="string[pyarrow]")
+    tm.assert_series_equal(ser_pyarrow, expected)
+
+    # Test with slice and missing values
+    ser_python = Series(["a", "b", None, "d", "e"], dtype="string[python]")
+    ser_pyarrow = Series(["X", "Y", None], dtype="string[pyarrow]")
+
+    ser_python[1:4] = ser_pyarrow
+    expected = Series(["a", "X", "Y", NA, "e"], dtype="string[python]")
+    tm.assert_series_equal(ser_python, expected)