module AbstractController::Caching::Fragments

def fragment_exist?(key, options = nil)

+key+ exists (see +expire_fragment+ for acceptable formats).
Check if a cached fragment from the location signified by 
def fragment_exist?(key, options = nil)
  return unless cache_configured?
  key = combined_fragment_cache_key(key)
  instrument_fragment_cache :exist_fragment?, key do
    cache_store.exist?(key, options)
  end
end