We have a bug-fix update for you as ReSharper Ultimate 2017.1.1 is now available for download.
You should definitely get this release if you have installed the latest Visual Studio 2017 update (April 6), and then when you tried to run your MSTest suite, you saw ReSharper telling you this:
Turns out that the latest Visual Studio update reverted a prior API change in a way that we didn’t expect, which kind of explains why ReSharper took the absolute latest Visual Studio build for an outdated one. The problem is now fixed, and you can run your MSTest suites again.
Apart from fixing the unit test runner issue, this update includes a small set of fixes in ReSharper C++.
dotMemory, dotCover, dotTrace and dotPeek have not received any bug fixes so far.