Yes, you are entirely correct. You can attach 12V and ground to those leads and the window will go one way or the other. Reverse the leads and the window will go the opposite way. If you are quite sure the switches are operational, then you should get no response to the application of 12V and ground to the terminals. If you do get a response, and the motor works properly, check to see if the switch will send power and ground to those leads.

There is another possibility:

The electrical system is fine and the motors work fine, however, the regulator has a damaged plastic sliding piece that means the glass will not go up and down.

Do some additional checking as described herein and report back.