Im unsure how you tell if they have broke, but it seems to be a common failure.
I get a scrapping/rubbing noise when going at slow speeds unually when reversing out my drive , i.e turning whilst reversing.
It sounds like a 'twanging' noise like the spring has broken because i thought that then i got it on the ramp at work and when i locked the wheels side to side u could here the bearings in the top mounts crunching which when there is weight isnt allowing the shock absorbers and springs to turn freely hence the 'twanging' noise.