From 60483ab2ab7c3a95ac776d5c6b73b5c3fc7962cb Mon Sep 17 00:00:00 2001
From: Li <litang_99@yahoo.com>
Date: Thu, 13 Nov 2025 07:00:17 +0000
Subject: [PATCH] address issue #52965: add tests

---
 pandas/tests/indexing/test_iloc.py | 16 ++++++++++++++++
 pandas/tests/indexing/test_loc.py  | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/pandas/tests/indexing/test_iloc.py b/pandas/tests/indexing/test_iloc.py
index ddb58ecbfa6f3..290a0c3205898 100644
--- a/pandas/tests/indexing/test_iloc.py
+++ b/pandas/tests/indexing/test_iloc.py
@@ -62,6 +62,22 @@ def test_iloc_getitem_int_and_list_int(self, key, frame_or_series, index, reques
         # array of ints (GH5006), make sure that a single indexer is returning
         # the correct type
 
+    @pytest.mark.parametrize(
+        "original_type, new_type",
+        [
+            (np.uint16, np.uint8),
+            (np.int32, np.int16),
+            (np.int64, np.uint64),
+            (np.int64, np.int16),
+        ],
+    )
+    def test_iloc_assign_preserve_dtype(self, original_type, new_type):
+        s = Series([10, 20, 30], index=list("abc"), dtype=original_type)
+        s.iloc[0:2] = np.array([100, 200], dtype=new_type)
+
+        expected = original_type
+        assert s.dtype == expected
+
 
 class TestiLocBaseIndependent:
     """Tests Independent Of Base Class"""
diff --git a/pandas/tests/indexing/test_loc.py b/pandas/tests/indexing/test_loc.py
index 8d59b0c026e0c..a2b79aff01294 100644
--- a/pandas/tests/indexing/test_loc.py
+++ b/pandas/tests/indexing/test_loc.py
@@ -277,6 +277,22 @@ def test_loc_empty_slice_assignment_with_datetime(self, data):
         df.loc[mask] = df
         tm.assert_frame_equal(df, expected)
 
+    @pytest.mark.parametrize(
+        "original_type, new_type",
+        [
+            (np.uint16, np.uint8),
+            (np.int32, np.int16),
+            (np.int64, np.uint64),
+            (np.int64, np.int16),
+        ],
+    )
+    def test_loc_assign_preserve_dtype(self, original_type, new_type):
+        s = Series([10, 20, 30], index=list("abc"), dtype=original_type)
+        s.loc["a":"b"] = np.array([100, 200], dtype=new_type)
+
+        expected = original_type
+        assert s.dtype == expected
+
 
 class TestLocBaseIndependent:
     # Tests for loc that do not depend on subclassing Base