Currently we have lots of pytests taking Arg to decide which (sysfs) path to work on. And there's no recommended format. For example, removable_storage uses a dict for type c or a / left or right / which port. Some sensors use glob pattern. Some others use a list of RE expressions for "best match". Also, many BFT-aware tests have a complicated bft_fixture dict arg.

One way to manage them is to always provide that in Device API. However, this implies we have to write lots of Python code and creating sub classes. Also, it seems more flexible if the pytest can work with arbitrary target path if needed.

As a result, one proposal is to create a config dedicated for storing "mapping from components to system path", for example 'components.json' that:

 {
   "light_sensor": "/sys/class/light_sensor/*",
   "usb": {
     "left": {
       "0": "/sys/class/usb/usb-1/1.0",
     }
     "right": {
     }
   }
   "usb_c": {
     "left": {
       "0": "/sys/class/usb/usb-1/1.0",
     }
   }
 }

And in Device API, provide a new top level function

 def GetComponentPath(name, *args):
  cfg = config_utils.LoadConfig('component')
  result = cfg.get(name, {})
  for subkey in args:
    result = result.get(subkey, {})
  return result

So in pytest, we always define arg

 Arg('component_name', str, 'The name of target component to test')

And in runTest:

 target_path = self.dut.GetComponentPath(self.args.component_name)
 print('sys node: %s' % target_path)