public void testTimeToLive_small() {
    CacheBuilder.newBuilder().expireAfterWrite(1, NANOSECONDS).build(identityLoader());
    // well, it didn't blow up.
  }

  public void testTimeToLive_setTwice() {
    CacheBuilder<Object, Object> builder =
        CacheBuilder.newBuilder().expireAfterWrite(3600, SECONDS);
    assertThrows(IllegalStateException.class, () -> builder.expireAfterWrite(3600, SECONDS));
  }