add test

paddle/operators/get_places_op.cc

@@ -35,7 +35,7 @@ class GetPlacesOp : public framework::OperatorBase {
                    out_var_name);
 
     auto &places = *(out_var->GetMutable<std::vector<platform::Place>>());
-    places.reserve(trainer_count);
+    places.resize(trainer_count);
     if (use_gpu) {
       for (int i = 0; i < trainer_count; i++) {
         places.emplace_back(platform::GPUPlace(i));

python/paddle/v2/fluid/tests/test_layers.py

@@ -170,6 +170,12 @@ class TestBook(unittest.TestCase):
             self.assertIsNotNone(layers.sequence_expand(x=x, y=y))
         print(str(program))
 
+    def test_get_places(self):
+        program = Program()
+        with program_guard(program):
+            x = layers.get_places(use_gpu=True, trainer_count=4)
+        print(str(program))
+
 
 if __name__ == '__main__':
     unittest.main()