For the latest documentation on Visual Studio 2017, see Visual Studio 2017 Documentation.
Visual Studio allows you to specify how more than one project is run when you start the debugger.
In the Solution Explorer, select the solution (the very top node). Right-click the node to get the context menu.
Select Properties. The Solution Property Pages dialog box opens.
Expand the Common Properties node, and click Startup Project.
Click Multiple Startup Projects and set the appropriatet actions. For more information, see NIB How to: Modify Project Properties and Configuration Settings.