I am sorry but Test Studio is not able to test .msi install files. It only supports testing WPF based desktop applications. It does not need access to the applications source code to test it. It will simulate the actions of a real user interacting with the application (mouse clicks and keyboard typing) and can verify what the application displays in its window. It is not able to test anything deeper than this, such as trying to test an internal method of function.
It does not work with other types of desktop applications. All of the above applies to both Test Studio full edition and Test Studio Express (our Visual Studio plug-in version).
All the best,
the Telerik team