Add simple test for GH 28448 (pandas-dev#29269)

Author: MarcoGorelli

pandas/tests/extension/test_categorical.py

@@ -223,6 +223,26 @@ def test_cast_category_to_extension_dtype(self, expected):
 
         tm.assert_series_equal(result, expected)
 
+    @pytest.mark.parametrize(
+        "dtype, expected",
+        [
+            (
+                "datetime64[ns]",
+                np.array(["2015-01-01T00:00:00.000000000"], dtype="datetime64[ns]"),
+            ),
+            (
+                "datetime64[ns, MET]",
+                pd.DatetimeIndex(
+                    [pd.Timestamp("2015-01-01 00:00:00+0100", tz="MET")]
+                ).array,
+            ),
+        ],
+    )
+    def test_consistent_casting(self, dtype, expected):
+        # GH 28448
+        result = pd.Categorical("2015-01-01").astype(dtype)
+        assert result == expected
+
 
 class TestArithmeticOps(base.BaseArithmeticOpsTests):
     def test_arith_series_with_scalar(self, data, all_arithmetic_operators):