update tests

Author: jbrockmendel

pandas/tests/reshape/merge/test_merge_asof.py

@@ -3488,7 +3488,6 @@ def test_merge_asof_array_as_on(unit):
             "ts": dti,
         }
     )
-    right["ts"] = right["ts"].astype("M8[ns]")
     ts_merge = pd.date_range(
         start=pd.Timestamp("2021/01/01 00:00"), periods=3, freq="1h", unit=unit
     )
@@ -3519,7 +3518,6 @@ def test_merge_asof_array_as_on(unit):
             "b": [4, 8],
         }
     )
-    expected["ts"] = expected["ts"].astype("M8[ns]")
     tm.assert_frame_equal(result, expected)
 
 

pandas/tests/reshape/test_qcut.py

@@ -264,7 +264,7 @@ def test_datetime_tz_qcut(bins):
         ],
         [
             date_range("20180101", periods=3),
-            DatetimeIndex(["2018-01-01", "2018-01-02", "2018-01-03"]).as_unit("ns"),
+            DatetimeIndex(["2018-01-01", "2018-01-02", "2018-01-03"]),
         ],
     ],
 )

pandas/tests/series/test_constructors.py

@@ -1083,16 +1083,16 @@ def test_constructor_dtype_datetime64_4(self):
     def test_constructor_dtype_datetime64_3(self):
         # if we passed a NaT it remains
         ser = Series([datetime(2010, 1, 1), datetime(2, 1, 1), NaT])
-        assert ser.dtype == "object"
+        assert ser.dtype == "M8[us]"
         assert ser[2] is NaT
         assert "NaT" in str(ser)
 
     def test_constructor_dtype_datetime64_2(self):
         # if we passed a nan it remains
         ser = Series([datetime(2010, 1, 1), datetime(2, 1, 1), np.nan])
-        assert ser.dtype == "object"
-        assert ser[2] is np.nan
-        assert "NaN" in str(ser)
+        assert ser.dtype == "M8[us]"
+        assert ser[2] is NaT
+        assert "NaT" in str(ser)
 
     def test_constructor_with_datetime_tz(self):
         # 8260