I created a new WCF Application. It has a svc file & a code behind, When I try to debug (F5) then I see the following.
To control the WCF Test Client auto-launch in Visual Studio 2015/2017 you can do the following:
Right-click the WCF Service Project in Solution Explorer, choose Properties, and click WCF Options tab. Clear the checkbox Start WCF Service Host when debugging another project in the same solution (that check box is enabled by default).