Add unittest for operator

test=develop

paddle/fluid/framework/operator.h

@@ -70,7 +70,7 @@ inline std::string GradVarName(const std::string& var_name) {
 }
 
 inline std::string OriginVarName(const std::string& grad_var_name) {
-  std::size_t pos = grad_var_name.find_last_of(kGradVarSuffix);
+  std::size_t pos = grad_var_name.rfind(kGradVarSuffix);
   if (pos == std::string::npos) {
     return grad_var_name;
   } else {

paddle/fluid/framework/operator_test.cc

@@ -289,11 +289,29 @@ TEST(OpKernel, multi_inputs) {
   op->Run(scope, cpu_place);
 }
 
-TEST(Functions, all) {
+TEST(VarNameTest, all) {
   std::string var_name("X");
   std::string grad_var_name = paddle::framework::GradVarName(var_name);
-  ASSERT_EQ(grad_var_name.c_str(), "X@GRAD");
+  ASSERT_EQ(grad_var_name, "X@GRAD");
   std::string original_var_name =
       paddle::framework::OriginVarName(grad_var_name);
-  ASSERT_EQ(original_var_name.c_str(), "X");
+  ASSERT_EQ(original_var_name, "X");
+  original_var_name = paddle::framework::OriginVarName(original_var_name);
+  ASSERT_EQ(original_var_name, "X");
+
+  std::string var_name_2("XYZ");
+  grad_var_name = paddle::framework::GradVarName(var_name_2);
+  ASSERT_EQ(grad_var_name, "XYZ@GRAD");
+  original_var_name = paddle::framework::OriginVarName(grad_var_name);
+  ASSERT_EQ(original_var_name, "XYZ");
+  original_var_name = paddle::framework::OriginVarName(original_var_name);
+  ASSERT_EQ(original_var_name, "XYZ");
+
+  std::string var_name_3("");
+  grad_var_name = paddle::framework::GradVarName(var_name_3);
+  ASSERT_EQ(grad_var_name, "@GRAD");
+  original_var_name = paddle::framework::OriginVarName(grad_var_name);
+  ASSERT_EQ(original_var_name, "");
+  original_var_name = paddle::framework::OriginVarName(original_var_name);
+  ASSERT_EQ(original_var_name, "");
 }