Add gtest for drnn

paddle/operators/CMakeLists.txt

@@ -191,8 +191,13 @@ op_library(sequence_pool_op DEPS sequence_pooling)
 op_library(lstm_op DEPS sequence2batch lstm_compute)
 op_library(conv_transpose_op DEPS vol2col)
 op_library(gru_op DEPS sequence2batch gru_compute)
-op_library(dynamic_recurrent_op SRCS dynamic_recurrent_op.cc rnn/recurrent_op_utils.cc
+if(WITH_TESTING)
+    op_library(dynamic_recurrent_op SRCS dynamic_recurrent_op.cc rnn/recurrent_op_utils.cc
+        DEPS net_op tensor_array gtest)
+else()
+    op_library(dynamic_recurrent_op SRCS dynamic_recurrent_op.cc rnn/recurrent_op_utils.cc
             DEPS net_op tensor_array)
+endif()
 op_library(recurrent_op SRCS recurrent_op.cc DEPS executor)
 
 list(REMOVE_ITEM GENERAL_OPS ${DEPS_OPS})