Detecting System Requirements
A VSPackage cannot function unless Visual Studio is installed. When you use Microsoft Windows Installer to manage the installation of your VSPackage, you can configure the installer to detect whether Visual Studio is installed. You can also configure it to check the system for other requirements, for example, a particular version of Windows or a particular amount of RAM.
To determine whether an edition of Visual Studio is installed, verify that the value of the Install registry key is (REG_DWORD) 1 in the appropriate folder, as listed in the following table. Note that there is a hierarchy of Visual Studio editions:
When a "higher" edition is installed, the registry keys for that edition as well as for "lower" editions are added. That is, if the Enterprise edition is installed, the Install key is set to 1 for Enterprise, as well as for Professional and Community editions. Therefore you need to check only for the "highest" edition you need.
In the 64-bit version of the registry editor, 32-bit keys are displayed under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\. The Visual Studio keys are under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\DevDiv\vs\Servicing\.
Visual Studio Enterprise 2015
Visual Studio Professional 2015
Visual Studio Community 2015
Visual Studio 2015 Shell (integrated and isolated)
Your VSPackage can't be registered correctly if Visual Studio is running when the VSPackage is installed. The installer must detect when Visual Studio is running and then refuse to install the program. Windows Installer doesn't let you use table entries to enable such detection. Instead, you must create a custom action, as follows: Use the EnumProcesses function to detect the devenv.exe process, and then either set an installer property that's used in a launch condition or conditionally display a dialog box that prompts the user to close Visual Studio.