std::set<string> factories_sorted;
  for (const auto& factory : GetFactories())
    factories_sorted.insert(factory.first);
  const char* comma = "";
  for (const string& factory : factories_sorted) {
    msg += comma + factory;
    comma = ", ";
  }
  msg += ")";

  return errors::InvalidArgument(msg.c_str());
}

static TracingContext* CreateTracingExecutionContext(const char* fn_name,

    uint64_t now = timer_seconds_();
    while (!lra_list_.empty()) {
      auto it = block_map_.find(lra_list_.back());
      if (now - it->second->timestamp <= max_staleness_) {
        // The oldest block is not yet expired. Come back later.
        break;
      }
      // We need to make a copy of the filename here, since it could otherwise
      // be used within RemoveFile_Locked after `it` is deleted.

  TFE_Op* non_comm_op = TFE_NewOp(ctx, "TestNonCommUnavailable", status);
  CHECK_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);
  TFE_TensorHandle* retval[1] = {};
  int num_retvals = 1;
  TFE_Execute(non_comm_op, retval, &num_retvals, status);
  EXPECT_EQ(TF_INTERNAL, TF_GetCode(status)) << TF_Message(status);
  TFE_DeleteOp(non_comm_op);