TST: astype cast via loc with nan values (pandas-dev#31861)

Author: hardikpnsp

pandas/tests/frame/methods/test_astype.py

@@ -136,6 +136,15 @@ def test_astype_cast_nan_inf_int(self, val, dtype):
         with pytest.raises(ValueError, match=msg):
             df.astype(dtype)
 
+    @pytest.mark.parametrize("dtype", ["Int64", "Int32", "Int16"])
+    @pytest.mark.parametrize("val", [np.nan])
+    def test_astype_cast_via_loc_nan_int(self, val, dtype):
+        # see GH#31861
+        expected = DataFrame({"a": ["foo"], "b": integer_array([val], dtype=dtype)})
+        result = DataFrame({"a": ["foo"], "b": [val]})
+        result.loc[:, "b"] = result.loc[:, "b"].astype(dtype)
+        tm.assert_frame_equal(result, expected)
+
     def test_astype_str(self):
         # see GH#9757
         a = Series(date_range("2010-01-04", periods=5))