Fix no cpus test (#5009)

python/ray/tests/conftest.py

@@ -56,6 +56,14 @@ def _ray_start(**kwargs):
     ray.shutdown()
 
 
+# The following fixture will start ray with 0 cpu.
+@pytest.fixture
+def ray_start_no_cpu(request):
+    param = getattr(request, "param", {})
+    with _ray_start(num_cpus=0, **param) as res:
+        yield res
+
+
 # The following fixture will start ray with 1 cpu.
 @pytest.fixture
 def ray_start_regular(request):

python/ray/tests/test_actor.py

@@ -842,7 +842,7 @@ def test_remote_functions_not_scheduled_on_actors(ray_start_regular):
     assert actor_id not in resulting_ids
 
 
-def test_actors_on_nodes_with_no_cpus(ray_start_regular):
+def test_actors_on_nodes_with_no_cpus(ray_start_no_cpu):
     @ray.remote
     class Foo(object):
         def method(self):