status = file->Tell(&position);
  EXPECT_EQ(status.code(), Code::OK);
  EXPECT_EQ(position, test_data.size());
}

TEST_P(ModularFileSystemTest, TestClose) {
  const std::string filename = GetURIForPath("a_file");
  std::unique_ptr<WritableFile> file;
  Status status = env_->NewWritableFile(filename, &file);
  if (!status.ok())