After a great interactive problem solving session with Ohad, we discovered that the problem was actually to do with the way I was referencing the TypeMock.msbuild.tasks file, and associated TypeMock.MSBuild.DLL.
You see, I had originally checked these file into VSTS _beside_ my TFSBuild.proj. I had done this several versions ago (3.5.0 or thereabouts) when the docs on how to setup for TeamBuild were a little sparse.
I then never updated the DLL or the tasks file as versions increased. Additionally, I believe that TypeMock needs access to a config.xml file within the typemock installation dir.
The upshot of it is, that the new help files describe how to setup typemock in a TeamBuild environment much better, and once I did that, all was clear.
I just like to reiterate my praise for this product and the support team behind it. Second to none.
As an aside, by successfully migrating to NUnit, NCover and Jetbrains TestRunner/Resharper, we have saved thousands of euros per developer-seat, as we no longer need to license VS2005 Team Test edition and the built in MSTest to get the type of testing and coverage metrics that we need. We would not have been able to make the migration, if TypeMock did not support these opensource tools.
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