added suggested testcases

Author: debnathshoham

pandas/tests/tools/test_to_datetime.py

@@ -177,6 +177,28 @@ def test_to_datetime_format_YYYYMMDD_overflow(self, input_s, expected):
         result = to_datetime(input_s, format="%Y%m%d", errors="coerce")
         tm.assert_series_equal(result, expected)
 
+    @pytest.mark.parametrize(
+        "data, format, expected",
+        [
+            ([pd.NA], "%Y%m%d%H%M%S", DatetimeIndex(["NaT"])),
+            ([pd.NA], None, DatetimeIndex(["NaT"])),
+            (
+                [pd.NA, "20210202202020"],
+                "%Y%m%d%H%M%S",
+                DatetimeIndex(["NaT", "2021-02-02 20:20:20"]),
+            ),
+            (["201010", pd.NA], "%y%m%d", DatetimeIndex(["2020-10-10", "NaT"])),
+            (["201010", pd.NA], "%d%m%y", DatetimeIndex(["2010-10-20", "NaT"])),
+            (["201010", pd.NA], None, DatetimeIndex(["2010-10-20", "NaT"])),
+            ([None, np.nan, pd.NA], None, DatetimeIndex(["NaT", "NaT", "NaT"])),
+            ([None, np.nan, pd.NA], "%Y%m%d", DatetimeIndex(["NaT", "NaT", "NaT"])),
+        ],
+    )
+    def test_to_datetime_with_NA(self, data, format, expected):
+        # GH#42957
+        result = to_datetime(data, format=format)
+        tm.assert_index_equal(result, expected)
+
     @pytest.mark.parametrize("cache", [True, False])
     def test_to_datetime_format_integer(self, cache):
         # GH 10178
@@ -383,26 +405,6 @@ def test_to_datetime_parse_timezone_keeps_name(self):
         expected = DatetimeIndex(["2010-01-01 12:00:00"], tz="UTC", name="foo")
         tm.assert_index_equal(result, expected)
 
-    @pytest.mark.parametrize(
-        "data, format, expected",
-        [
-            ([pd.NA], "%Y%m%d%H%M%S", DatetimeIndex(["NaT"])),
-            ([pd.NA], None, DatetimeIndex(["NaT"])),
-            (
-                [pd.NA, "20210202202020"],
-                "%Y%m%d%H%M%S",
-                DatetimeIndex(["NaT", "2021-02-02 20:20:20"]),
-            ),
-            (["201010", pd.NA], "%y%m%d", DatetimeIndex(["2020-10-10", "NaT"])),
-            (["201010", pd.NA], "%d%m%y", DatetimeIndex(["2010-10-20", "NaT"])),
-            (["201010", pd.NA], None, DatetimeIndex(["2010-10-20", "NaT"])),
-        ],
-    )
-    def test_to_datetime_with_pdNA(self, data, format, expected):
-        # GH#42957
-        result = to_datetime(data, format=format)
-        tm.assert_index_equal(result, expected)
-
 
 class TestToDatetime:
     @pytest.mark.parametrize(