You can test WPF applications without any special preparations. You can also access individual objects of WPF applications, their internal properties and methods from your tests.
However, in certain cases, you need to prepare your .NET application before testing it:
You can test a XAML browser application (XBAP) if it has certain security permissions. For more information, see Preparing XAML Browser Applications for Testing.
You can test a WPF application that is launched from a web server by using Internet Explorer and no-touch deployment if the application has the Full Trust permission. For details, see Preparing Network and No-Touch Deployment .NET Applications for Testing.