pass multiple forward backward

paddle/framework/executor_test.cc

@@ -279,9 +279,11 @@ TEST_F(ExecutorTesterRandom, GPU) {
   std::unique_ptr<Executor> executor(new Executor(places));
 
   executor->Run(init_pdesc_, GetGlobalScope(), 0);
+  for (int batch_id = 0; batch_id < 3; batch_id++) {
     executor->Run(pdesc_, GetGlobalScope(), 0);
     std::vector<std::vector<float>> result = GetFetchVariable<float>();
   }
+}
 
 TEST_F(ExecutorTesterFeedAndFetch, GPU) {
   std::vector<Place> places;