std::vector<size_t> lens(expected.size());
    std::unique_ptr<char[]> storage(new char[m.total_size]);
    TF_OperationGetAttrStringList(op, tensorflow::kColocationAttrName,
                                  values.data(), lens.data(), expected.size(),
                                  storage.get(), m.total_size, s_);
    EXPECT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);

    EXPECT_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);
    TFE_DeleteTensorHandle(n);
    n = n_gpu;
  }

  TFE_TensorHandle* m = TestMatrixTensorHandle100x100(ctx);

  // Store pointer to raw buffer for validation of forwarding behaviour.
  TF_Tensor* orig = TFE_TensorHandleResolve(n, status);
  void* orig_ptr = TF_TensorData(orig);
  TF_DeleteTensor(orig);

  TFE_Op* add_op = AddOp(ctx, n, m);