add concat function dtype test

Signed-off-by: Liang Yan <[email protected]>

Author: liang3zy22

pandas/tests/arithmetic/test_datetime64.py

@@ -2436,3 +2436,33 @@ def test_dt64arr_addsub_object_dtype_2d():
 
     assert result2.shape == (4, 1)
     assert all(td._value == 0 for td in result2.ravel())
+
+
+def test_concat_float_datetime64():
+    # GH#32934
+    df_time = pd.DataFrame({"A": pd.array(["2000"], dtype="datetime64[ns]")})
+    df_float = pd.DataFrame({"A": pd.array([1.0], dtype="float64")})
+
+    expected = pd.DataFrame(
+        {
+            "A": [
+                pd.array(["2000"], dtype="datetime64[ns]")[0],
+                pd.array([1.0], dtype="float64")[0],
+            ]
+        },
+        index=[0, 0],
+    )
+    result = pd.concat([df_time, df_float])
+    tm.assert_frame_equal(result, expected)
+
+    expected = pd.DataFrame({"A": pd.array([], dtype="object")})
+    result = pd.concat([df_time.iloc[:0], df_float.iloc[:0]])
+    tm.assert_frame_equal(result, expected)
+
+    expected = pd.DataFrame({"A": pd.array([1.0], dtype="object")})
+    result = pd.concat([df_time.iloc[:0], df_float])
+    tm.assert_frame_equal(result, expected)
+
+    expected = pd.DataFrame({"A": pd.array(["2000"], dtype="datetime64[ns]")})
+    result = pd.concat([df_time, df_float.iloc[:0]])
+    tm.assert_frame_equal(result, expected)