ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
  }

  void VerifyCollocation(TF_Operation* op,
                         const std::vector<string>& expected) {
    TF_AttrMetadata m =
        TF_OperationGetAttrMetadata(op, tensorflow::kColocationAttrName, s_);
    if (expected.empty()) {
      ASSERT_EQ(TF_INVALID_ARGUMENT, TF_GetCode(s_)) << TF_Message(s_);
      EXPECT_EQ("Operation 'add' has no attr named '_class'.",