From 7c02964b838f4504ad98420945c027c983f4e984 Mon Sep 17 00:00:00 2001
From: Ashar <asharmalik.khan@gmail.com>
Date: Fri, 28 Feb 2025 15:31:41 -0500
Subject: [PATCH] TST: Add test for groupby with datetime and NaT values

---
 pandas/tests/groupby/test_groupby.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py
index e08ddf750b00c..4b1f23c1f755e 100644
--- a/pandas/tests/groupby/test_groupby.py
+++ b/pandas/tests/groupby/test_groupby.py
@@ -2978,3 +2978,21 @@ def test_groupby_multi_index_codes():
 
     index = df_grouped.index
     tm.assert_index_equal(index, MultiIndex.from_frame(index.to_frame()))
+
+
+def test_groupby_datetime_with_nat():
+    # GH##35202
+    df = DataFrame(
+        {
+            "a": [
+                to_datetime("2019-02-12"),
+                to_datetime("2019-02-12"),
+                to_datetime("2019-02-13"),
+                pd.NaT,
+            ],
+            "b": [1, 2, 3, 4],
+        }
+    )
+    grouped = df.groupby("a", dropna=False)
+    result = len(grouped)
+    assert result == 3