status = env_->GetChildren(dirpath, &children);
  EXPECT_PRED2(UnimplementedOrReturnsCode, status, Code::OK);
  if (!status.ok()) GTEST_SKIP() << "GetChildren() not supported: " << status;

  // All entries must show up in the vector.
  // Must contain only the last name in filenames and dirnames.
  const std::vector<std::string> expected_children = {"a_file", "another_file",

    string expected_msg =
        "No gradient defined for op: TestOpWithNoGradient. Please see "
        "https://www.tensorflow.org/code/"
        "tensorflow/cc/gradients/README.md"
        " for instructions on how to add C++ gradients.";
    EXPECT_EQ(expected_msg, TF_Message(s_));
  }

  // Run the graph and ensure that the gradient values are as expected.
  void RunGraphsAndCompareOutputs(TF_Output* grad_outputs,