public async Task GetMessages_QueueCheckThrowsTransientError_ReturnsBackoffResult() { CancellationToken cancellationToken = new CancellationToken(); var exception = new StorageException( new RequestResult { HttpStatusCode = 503 }, string.Empty, new Exception()); _mockQueue.Setup(p => p.GetMessagesAsync(It.IsAny <int>(), It.IsAny <TimeSpan>(), null, null, cancellationToken)).Throws(exception); var result = await _listener.ExecuteAsync(cancellationToken); Assert.NotNull(result); await result.Wait; }