[asv] Add benchmark for ray.wait (#2625)

* Add benchmarks for ray.wait

* Fix bug

python/benchmarks/benchmarks.py

@@ -3,7 +3,6 @@ from __future__ import division
 from __future__ import print_function
 
 import ray
-import ray.test.test_functions as test_functions
 
 
 def setup():
@@ -12,6 +11,11 @@ def setup():
         setup.is_initialized = True
 
 
+@ray.remote
+def trivial_function():
+    return 1
+
+
 class TimeSuite(object):
     """An example benchmark."""
 
@@ -37,10 +41,10 @@ class MemSuite(object):
 
 class MicroBenchmarkSuite(object):
     def time_submit(self):
-        test_functions.empty_function.remote()
+        trivial_function.remote()
 
     def time_submit_and_get(self):
-        x = test_functions.trivial_function.remote()
+        x = trivial_function.remote()
         ray.get(x)
 
     def time_put(self):