# Test application and infrastructure as a whole

The importance of testing the integration between your application and infrastructure should not be neglected when you’re developing a cloud application, especially on a serverless platform. When you’re using a cloud workflow service, like AWS Step Function for example, application logic will leak into your infrastructure — this is an IaC, not an application configuration, therefore it can’t be tested just from the application point of view.

Cloud sandbox allows you to test your application and infrastructure as a whole stack, altogether. That means, if there’s a system behaviour that you’d like to assert, you’ll be able to test it before you push changes to mainline.

Even though you can achieve a similar test coverage with Fake sandbox, there is a risk of “but it works on my machine” — where integration doesn’t work in the cloud. It’s difficult to fake the cloud services well because Can we fake a cloud platform?. This late integration issue introduces a slow feedback cycle as you’ll only discover problems further in your deployment pipeline.