Recently, I experienced a problem trying to get the CodeRush test runner to run on my machine, here's the full story.
I was working on an MVC project that had no test project attached, so I added a "Class Library" project to the solution, added NUnit to the project via NuGet and started writing some tests. Unfortunatley, after writing the tests I couldn't get any of them to run. If I selected 'Run Tests' from the project menu Visual Studio told me it couldn't find any tests, and the test tube icons that CodeRush adds to unit tests were not apperaing next to my tests.
After faffing around for quite some time I realised you need to install NUnit first before the test runner will work. So I headed over to www.nunit.org and installed NUnit 1.5. After NUnit has been installed you can check that it's set-up and ready to run alongside CodeRush by selecting the 'DevExpress' menu in Visual Studio then choosing the 'Options' option then choosing the 'Unit Testing' node and the 'Test Runner' option. You should then see something similar to this -
You can (just about) see from the screenshot above that the version of CodeRush I'm running only lists versions of NUnit up to 1.5, so I chose to install the 1.5 version rather than the newer 1.6 version. I presume if I updated CodeRush to the latest build it would recognise version 1.6.
Having installed NUnit all I needed to do was remove the reference to NUnit 1.6 from my test project and add a reference to the 1.5 version to match the installed version of Nunit on the machine. Once I'd done this everything clicked into place and the icons appeared!
Before solving the problem, I Googled for a solution for quite some time, and couldn't find anybody who'd had a similar experience, but it's possible that I'm the only person dim enough not to realise that you need to install the test framework of your choice to get the the test runner to work. I guess if I'd installed NUnit via the traditional 'msi' route rather than using NuGet (which I presume only installs the NUnit dll) then I'd have never encountered the problem.