I defined two tests in VisualGDB.  The tests are defined in the file .vgdbtests.  I see the definitions of each test when I open the file.

But the tests did not show up in the Test Explorer window.

Also, the error message below is displayed in Visual Studio 2019.

[13:25:52.950 Info] No supported test adapters are referenced by unit test projects in this solution. If you have a test project, add a NuGet reference to a test adapter corresponding to the test framework used in order to run the tests. If you already have the required NuGet reference in your test project, performing a NuGet restore may resolve the issue.