TF_Operation* feed = Placeholder(graph, s);
  ASSERT_EQ(TF_OK, TF_GetCode(s)) << TF_Message(s);

  // Test TF_Operation*() query functions.
  EXPECT_EQ(std::string("feed"), std::string(TF_OperationName(feed)));
  EXPECT_EQ(std::string("Placeholder"), std::string(TF_OperationOpType(feed)));
  EXPECT_EQ(std::string(""), std::string(TF_OperationDevice(feed)));
  EXPECT_EQ(1, TF_OperationNumOutputs(feed));