TF_CAPI_EXPORT extern TF_AttrMetadata TF_OperationGetAttrMetadata(
    TF_Operation* oper, const char* attr_name, TF_Status* status);

// Fills in `value` with the value of the attribute `attr_name`.  `value` must
// point to an array of length at least `max_length` (ideally set to
// TF_AttrMetadata.total_size from TF_OperationGetAttrMetadata(oper,
// attr_name)).

    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'.",