More flaky marks

Author: dcherian

xarray/tests/test_backends.py

@@ -2990,11 +2990,6 @@ def test_chunked_cftime_datetime(self) -> None:
             assert original.chunks == actual.chunks
 
     def test_vectorized_indexing_negative_step(self) -> None:
-        if not has_dask:
-            pytest.xfail(
-                reason="zarr without dask handles negative steps in slices incorrectly"
-            )
-
         super().test_vectorized_indexing_negative_step()
 
 
@@ -3824,9 +3819,10 @@ def skip_if_not_engine(engine):
         pytest.importorskip(engine)
 
 
+# Flaky test. Very open to contributions on fixing this
 @requires_dask
 @pytest.mark.filterwarnings("ignore:use make_scale(name) instead")
-@pytest.mark.xfail(reason="Flaky test. Very open to contributions on fixing this")
+@pytest.mark.flaky
 def test_open_mfdataset_manyfiles(
     readengine, nfiles, parallel, chunks, file_cache_maxsize
 ):
@@ -4529,7 +4525,8 @@ def test_open_multi_dataset(self) -> None:
             ) as actual:
                 assert_identical(expected, actual)
 
-    @pytest.mark.xfail(reason="Flaky test. Very open to contributions on fixing this")
+    # Flaky test. Very open to contributions on fixing this
+    @pytest.mark.flaky
     def test_dask_roundtrip(self) -> None:
         with create_tmp_file() as tmp:
             data = create_test_data()