const std::string translated_name =
        tensorflow::io::JoinPath(root_dir_, path);
    // We have already checked `GetParam().empty()` in
    // `ModularFileSystemTest()`. root_dir_ should contain `GetParam() + "://"`
    // if it isn't empty.
    return translated_name;
  }

  // Converts absolute paths to paths relative to root_dir_.
  StringPiece GetRelativePath(StringPiece absolute_path) {

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
// there are more than one), or "" otherwise.
string GPUDeviceName(TF_Session* session) {