New Op Test framework. (#4962)

Pass all forward op test

Author: Yang Yang(Tony)

paddle/operators/crop_op.cc

@@ -59,7 +59,8 @@ class CropOpMaker : public framework::OpProtoAndCheckerMaker {
              "The input should be a k-D tensor(k > 0 and k < 7)");
     AddInput("Y",
              "The input used as reference for cropping"
-             " with the same dimension as X. ");
+             " with the same dimension as X. ")
+        .AsDispensable();
     AddOutput("Out",
               "The output of crop op "
               "with the same dimension as X.");

paddle/operators/fc_op.cc

@@ -54,8 +54,7 @@ class GRUUnitOp : public framework::OperatorWithKernel {
     PADDLE_ENFORCE_EQ(
         weight_width, frame_size * 3,
         "The shape of Weight matrix must be [frame_size, frame_size * 3].");
-    auto bias = Input("Bias");
-    if (bias != framework::kEmptyVarName) {
+    if (ctx->HasInput("Bias")) {
       auto bias_dims = ctx->GetInputDim("Bias");
       int bias_height = bias_dims[0];
       int bias_width = bias_dims[1];
@@ -89,7 +88,8 @@ class GRUUnitOpMaker : public framework::OpProtoAndCheckerMaker {
              "weights of output candidate with shape [frame_size, frame_size]");
     AddInput("Bias",
              "(Tensor) Bias vector with shape [1, frame_size * 3] concating "
-             "bias of the update gate, reset gate and output candidate.");
+             "bias of the update gate, reset gate and output candidate.")
+        .AsDispensable();
     AddOutput("Gate",
               "(Tensor) Matrix with shape [batch_size, frame_size * 3] for the "
               "output of update gate, reset gate and output candidate")