Further to what Randomizer stated:
Stand just south of the sentinel you need to talk to in order to begin the test, but make sure you wait until the patrols are not near (off the screen to the left and right). I was able to talk to him, begin the test, and head directly south (toward an open door) and pass the test without ever entering combat mode. I believe I casted haste on everyone prior, but I doubt it was necessary.