namespace tensorflow {
TF_Tensor* TF_TensorFromTensor(const Tensor& src, absl::Status* status);
absl::Status TF_TensorToTensor(const TF_Tensor* src, Tensor* dst);

namespace {

static void ExpectHasSubstr(StringPiece s, StringPiece expected) {
  EXPECT_TRUE(absl::StrContains(s, expected))
      << "'" << s << "' does not contain '" << expected << "'";
}

// Returns the GPU device name if there is one (with arbitrary tie breaking if

    TestUnavailableErrorOp);
REGISTER_KERNEL_BUILDER(
    Name("TestCommUnavailable").Device(tensorflow::DEVICE_DEFAULT),
    TestUnavailableErrorOp);

string FunctionWithErrorOp(const tensorflow::StringPiece op_name) {
  const std::string& func_str =
      "    signature {"
      "      name: 'FunctionWith__OP_NAME__'"
      "      output_arg {"
      "        name: 'out'"
      "        type: DT_STRING"