Add test cases

Author: dsaxton

pandas/tests/dtypes/test_inference.py

@@ -1100,11 +1100,14 @@ def test_date(self):
         [
             [date(2020, 1, 1), pd.Timestamp("2020-01-01")],
             [pd.Timestamp("2020-01-01"), date(2020, 1, 1)],
+            [date(2020, 1, 1), pd.NaT],
+            [pd.NaT, date(2020, 1, 1)],
         ],
     )
-    def test_infer_dtype_date_order_invariant(self, values):
+    @pytest.mark.parametrize("skipna", [True, False])
+    def test_infer_dtype_date_order_invariant(self, values, skipna):
         # https://github.com/pandas-dev/pandas/issues/33741
-        result = lib.infer_dtype(values, skipna=True)
+        result = lib.infer_dtype(values, skipna=skipna)
         assert result == "date"
 
     def test_is_numeric_array(self):