Replaces unittest annotation with setting __test__ = False to prevent…

… nosetest from trying to run the method.

sdks/python/apache_beam/runners/dataflow/dataflow_runner.py

@@ -30,7 +30,6 @@
 import threading
 import time
 import traceback
-import unittest
 import urllib
 from builtins import hex
 from collections import defaultdict
@@ -1196,7 +1195,6 @@ def run__NativeWrite(self, transform_node, options):
          PropertyNames.STEP_NAME: input_step.proto.name,
          PropertyNames.OUTPUT_NAME: input_step.get_output(input_tag)})
 
-  @unittest.skip("This is not a test, despite the name.")
   def run_TestStream(self, transform_node, options):
     from apache_beam.portability.api import beam_runner_api_pb2
     from apache_beam.testing.test_stream import ElementEvent
@@ -1239,6 +1237,10 @@ def run_TestStream(self, transform_node, options):
         PropertyNames.OUTPUT_NAME: PropertyNames.OUT
     }])
 
+  # We must mark this method as not a test or else its name is a matcher for
+  # nosetest tests.
+  run_TestStream.__test__ = False
+
   @classmethod
   def serialize_windowing_strategy(cls, windowing):
     from apache_beam.runners import pipeline_context