In Visual Studio 2015 Enterprise command "Create IntelliTest" or "Run Intelltest" doesn't appear on the popup menu in project type "Class Library (Package)".
These are not supported yet. We are tracking that ask here: https://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/9571569-enable-lntellitest-support-of-shared-projects. Please consider voting.