public async Task GetNumberOfMessagesOnQueue_ShouldReturnNumberOfMessagesOnQueue_WhenMessageExists() { var client = new SQSClientMock("mockEndpoint", "mockRegion"); await client.CreateStandardFifoQueueAsync(FifoQueueName); await client.SendMessageAsync("Foo", FifoQueueName); var actual = await client.GetNumberOfMessagesOnQueue(FifoQueueName); Assert.Equal(FifoQueueName, actual.QueueName); Assert.Equal(1, actual.ApproximateNumberOfMessages); }