Today I switched from Visual Studio 2013 to Visual Studio 2015 and I am since experiencing problems with running unit tests developed in MSTest. I am working on a solution with 4 projects and 4 test projects, with a total of about 11.000 unit tests.
Now, upon building of the solution and a fresh start of Visual Studio, the IDE usually (not always) discovers all tests. When I try to run them however, I see a lot of error messages in the output window telling me that duplicate tests were found, reducing the number of found tests in the solution. Then, when the tests are performed, I receive a lot of error notifications telling me about unknown tests having reported a problem and they are therefore ignored.
This leads to the discovered tests rapidly declining, making debugging virtually impossible (since even if a test is found, it is most of the time lost when I let it run in debug mode).
On top of that, Visual Studio 2015 frequently crashes when I try to run one (or many) tests, not giving me any indication about what happened but only the windows "Visual Studio is no longer working" dialog as soon as I click on run.
I'm suspecting the problem is that I have about 10 test classes with each about 400 test methods (which were auto generated), so I just divided them up into each 5 classes with about 80 methods, but that did not change the situation.
I've found the description of the problem in this question to be somewhat similar and followed the proposed solution, but this does not work permanently for me.
I'm using ReSharper as an extension in Visual Studio, I don't see the behaviour here.
