update tests

Author: jbrockmendel

pandas/tests/indexes/datetimes/methods/test_unique.py

@@ -34,9 +34,9 @@ def test_index_unique(rand_series_with_duplicate_datetimeindex):
             datetime(2000, 1, 4),
             datetime(2000, 1, 5),
         ],
-        dtype="M8[ns]",
+        dtype=index.dtype,
     )
-    assert uniques.dtype == "M8[us]"  # sanity
+    assert uniques.dtype == index.dtype  # sanity
     tm.assert_index_equal(uniques, expected)
     assert index.nunique() == 4
 

pandas/tests/indexes/datetimes/test_date_range.py

@@ -315,7 +315,7 @@ def test_date_range_convenience_periods(self, unit):
             ["2018-04-24 00:00:00", "2018-04-25 12:00:00", "2018-04-27 00:00:00"],
             dtype=f"M8[{unit}]",
             freq=None,
-        ).as_unit("ns")
+        )
 
         tm.assert_index_equal(result, expected)