Microsoft introduced a TestServer component that allows integration testing (link).
- Wikipedia article (link)
- MSDN article (link)
- Unit Testing and Integration Testing in Business Applications (link)
- Integration Testing Your ASP.NET MVC Application (link)
- ASP.NET Web API integration testing with in-memory hosting (link)
Testing web projects may require working around issues like HttpContext.
- Unit testing a class dependent on HttpContext (link)