Two comments related with this method:

  1. `loadNetworkInterfaces` is an asynchronous method. To simulate this, add a time out where you will assign the proper variable.
  2. Furthermore, it is assigning `Common` witch is not part of the mock. To solve this, instead of returning a raw object. Assign this object to a variable (i.e. `var mockCommon = { /* Your object */ };), then use this variable to access `allNetworkInterfaces` and assign the array, and finally return the variable.

This way you will certainly know the property you are touching is YOUR property and don't rely on the use the developer made of your mockup.