(For an overview of this series, please read this post.)
In order for you Windows 8 Metro style app to be published to the Windows Store it must pass Microsoft’s testing process. Fortunately, for you, you can run your apps through a number of Microsoft’s tests by simply using the Windows App Certification Kit (ACK). The ACK is used to validate compliance with certification requirements, and replaces the Windows Software Logo Kit (WSLK) used for validation in the Windows 7 Software Logo program. Desktop, desktop device, and Metro style apps can be certified. The Windows ACK is included in the Windows Software Development Kit (SDK) and the Windows SDK for Metro style apps.
The ACK tests your Metro style applications in the following categories:
The app must not crash or hang. App failures, such as crashes and hangs, disrupt and frustrate customers. Eliminating such failures improves app stability and reliability, and overall, provides customers with a better experience.
The app manifest must contain all the required attributes.
Windows security features
The app must use Windows security features.
Supported platform APIs
The app must use only APIs from the Windows Software Development Kit (SDK) for Metro style Apps.
The app should have a fast and responsive startup experience while consuming a reasonable amount of system resources (CPU, file IO, memory, and so on) to enable fast switching and multitasking between previously unopened apps.
The app should have a fast and responsive suspend experience while consuming a reasonable amount of system resources (CPU, File IO, Memory, and so on) and making sure that resources are released efficiently.
App package resource validation
The app manifest must have valid resources defined in the resources.pri file, as explained in the App package manifest schema.
.NET version check
The app must use .NET 4.5 or later.
To be clear, desktop (non-Metro style) apps do not have to be certified to run on Windows 8. However, desktop apps, like Metro apps, must be certified in order to be listed in the Windows Store.