}

TEST(ExpiringLRUCacheTest, MaxEntries) {
  // max_age of 0 means nothing will be cached.
  tf_gcs_filesystem::ExpiringLRUCache<int> cache1(0, 4);
  cache1.Insert("a", 1);
  int value = 0;
  EXPECT_FALSE(cache1.Lookup("a", &value));
  // Now set max_age = 1 and verify the LRU eviction logic.
  tf_gcs_filesystem::ExpiringLRUCache<int> cache2(1, 4);
  cache2.Insert("a", 1);
  cache2.Insert("b", 2);
  cache2.Insert("c", 3);

///
/// This class is thread safe.
template <typename T>
class ExpiringLRUCache {
 public:
  /// A `max_age` of 0 means that nothing is cached. A `max_entries` of 0 means
  /// that there is no limit on the number of entries in the cache (however, if
  /// `max_age` is also 0, the cache will not be populated).
  ExpiringLRUCache(uint64_t max_age, size_t max_entries,

      ABSL_GUARDED_BY(block_cache_lock);
  uint64_t block_size;  // Reads smaller than block_size will trigger a read
                        // of block_size.
  std::unique_ptr<ExpiringLRUCache<GcsFileStat>> stat_cache;
  GCSFile(google::cloud::storage::Client&& gcs_client);
  // This constructor is used for testing purpose only.
  GCSFile(google::cloud::storage::Client&& gcs_client, bool compose,

  if (stat_cache_max_entries_env &&
      absl::SimpleAtoi(stat_cache_max_entries_env, &value)) {
    stat_cache_max_entries = static_cast<size_t>(value);
  }
  stat_cache = std::make_unique<ExpiringLRUCache<GcsFileStat>>(
      stat_cache_max_age, stat_cache_max_entries);
}

GCSFile::GCSFile(google::cloud::storage::Client&& gcs_client, bool compose,