In this video, you will get a clear understanding of MSTest v2 usage in Visual Studio 2019 by Ref. It shows the Ref. assembly changes and also showing additional features supported through MSTest v2 + Visual Studio 2019. One more interesting feature of extending MSTest v2 also explained in this video.

MS Test has been there for a long time and now its v2 is available as open source. If you are using an older version, then remove the "microsoft.visualstudio.qualitytools.unittestframework" Ref. to add new Ref of "MSTest.TestFramework" and "MSTest.TestAdapter" from NuGet package. MSTest.TestFramework itself implements the testing frameworks and its contracts. Visual Studio uses a framework called Visual Studio Test Platform to load test adapters. To discover or execute test cases, VSTest would call the test adapters based on your project configuration. So MSTest.TestAdapter exists for that purposes.