private async Task <IEnumerable <RsaKey> > LoadKeysAsync()
        {
            var storedKeys = await _repository.LoadKeysAsync();

            IEnumerable <RsaKey> keys = storedKeys.Select(_serializer.Deserialize).Where(x => x != null).ToArray();

            return(await DeleteRetiredKeysAsync(keys));
        }
        private async Task <IEnumerable <SerializedKey> > RunConcurrentServices(IEnumerable <SerializedKey> existingKeys)
        {
            _repository = new TestKeyRepository(existingKeys);

            var service1 = NewService();
            var service2 = NewService();

            Task.WaitAll(
                Task.Run(() => service1.GetAllKeysAsync().Wait(ServiceExecutionTimeout)),
                Task.Run(() => service2.GetAllKeysAsync().Wait(ServiceExecutionTimeout)));

            return(await _repository.LoadKeysAsync());
        }