Fix test_deprecation_warning in gpuCI (dask-contrib#248)

* Try to assess wher extra warning is coming from

* Use assertion to print out warning messages

* Filter out non deprecation warnings from deprecation test

* Try passing gpu argument directly to register_dask_table

Author: charlesbluca

tests/unit/test_context.py

@@ -40,13 +40,10 @@ def test_deprecation_warning(gpu):
     c = Context()
     data_frame = dd.from_pandas(pd.DataFrame(), npartitions=1)
 
-    if gpu:
-        data_frame = dask_cudf.from_dask_dataframe(data_frame)
-
     with warnings.catch_warnings(record=True) as w:
         warnings.simplefilter("always")
 
-        c.register_dask_table(data_frame, "table")
+        c.register_dask_table(data_frame, "table", gpu=gpu)
 
         assert len(w) == 1
         assert issubclass(w[-1].category, DeprecationWarning)