Mock Link allows you to create and stop links to multiple simulated (mock) vehicles in QGroundControl debug builds.
The simulation does not support flight, but does allow easy testing of:
It is particularly useful for unit testing error cases for mission upload/download.
To use Mock Link:
Create a debug build by building the source.
Access Mock Link by selecting the Application Settings icon in the top toolbar and then Mock Link in the sidebar:
The buttons in the panel can be clicked to create a vehicle link of the associated type.
Click the Stop one Mock Link to stop the currently active vehicle.
Using Mock Link is then more or less the same as using any other vehicle, except that the simulation does not allow flight.