Blueski
Not sure what you mean by formal testing. There are three hoops to jump through to attain an instrument rating. Yes there is a written test. It is only as hard as you want it to be. The govt is required to publish all the test questions and many companies will sell you them in book form to study. There is also a practical test in the aircraft to check tolerances. Lastly there is a oral exam in which the examiner peppers you with questions and scenarios for what ever time frame they deem suitable.
Flying femme
What good is the IMC rating? Is it for someone with a limited budget? Almost sounds like the recreational pilot certificate over here, an intro with loads of restrictions.