<Service Include="{B4F97281-0DBD-4835-9ED8-7DFB966E87FF}" /> in csproj file

For TL;DR:

“This behavior is intentional.”

Long Version:

As described in this answer from Microsoft:

This behavior is intentional.

To support third-party test frameworks, like NUnit and XUnit, Visual Studio 2012 loaded Test Explorer on solution open, regardless of whether it contained test projects. This added seconds of delay to startup and solution open scenarios for all users, majority of whom don’t use tests.

In Visual Studio 2013, we changed it so that Test Explorer package is loaded only when the solution contains one or more test projects. Test projects are identified in two different ways. Projects created from one of the built-in unit test project templates are identified using project type GUIDs. Other types of projects, such as Class Library project with XUnit or NUnit tests, are identified by Test Explorer during first test discovery and “tagged” with the <Service/> item.

To workaround this issue:

Personally I don’t like this service added to my project files and I think having it is more like a workaround rather than a proper solution. So marking your test projects as test projects seems more correct to me and this can be achieved by adding this to the first PropertyGroup:

<ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
<TestProjectType>UnitTest</TestProjectType>

{3AC096D0-A1C2-E12C-1390-A8335801FDAB} means Test Project and {FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}

  • C#. For other project type guids go here

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