Unfortunately there are no nice, unified tools (that I've found anyway) for testing CF apps. No one provides mocking, since the CF CLR is missing things like Emit, making the taks difficult for a small market.
Microsoft provides unit test capabilities in Studio and Team Foundation Server for smart device apps, but they don't do UI, debugging the tests is amazingly painful and just running tests is slow, so they tend to be good for regression tests and not much else.
Microsoft provides some tools and a tool framework for desktop-driven testing in the CE Test Kit (CETK), including the DATK that Alan alludes to. They also provide things like the Hopper Test Tool, which they use as part of their logo testing.
If none of these seem to work for you, a fairly rapid way to set up testing that's still driven from the PC (which I think all testing should, else it tends to be painful to run, tough to automate, and a bear to log pass/failure data), the you can use the CoreCon APIs or the Remote Tools Framework to build your communication pipe and test framework.
I sincerely hope that the VSD (Studio for Devices) team is dogfooding TFS and that we get a much richer toolset with the next release of Studio.
