code sample for pandas-dev#40841

Author: simonjayhawkins

bisect/40841.py

@@ -0,0 +1,34 @@
+# BUG: AssertionError: <class 'pandas.core.arrays.datetimes.DatetimeArray'> on
+# concat #40841
+
+import numpy as np
+import pandas as pd
+
+import pandas.testing as tm
+
+print(pd.__version__)
+
+right = pd.DataFrame(
+    data={"C": [0.5274]},
+    index=pd.DatetimeIndex(
+        ["2021-04-08 21:21:14+00:00"],
+        dtype="datetime64[ns, UTC]",
+        name="Time (UTC)",
+        freq=None,
+    ),
+)
+
+left = pd.DataFrame(
+    data={"A": [None], "B": [np.nan]},
+    index=pd.Index([None], dtype="object", name="Maybe Time (UTC)"),
+)
+
+result = pd.concat([left, right], axis="columns")
+print(result)
+
+expected = pd.DataFrame(
+    {"A": [None, None], "B": [np.nan, np.nan], "C": [np.nan, 0.5274]},
+    index=pd.Index([pd.NaT, pd.Timestamp("2021-04-08 21:21:14+00:00")], dtype="object"),
+)
+
+tm.assert_frame_equal(result, expected)