The Speed test room challenge has a rare chance of spawning. As of April 4, 2017, the best place for this test to spawn on Lua is Plato, the exterminate mission.
If all you are looking for is the speed test, go to Plato and speed run through the tileset. If you don't find it, abort and redo the mission. You may have to do this dozens to fifty or more times, so the abort method will speed things up.
To find the test room, you start by finding a room (approximately 50 feet square, 15.24 meters), with two thumper orbs and laser discs on the left and right hand walls. There are maybe ten or more laser discs on each wall. There will be a disc straight up on the far wall from where you enter. To trigger the two areas that you need to run through, shoot that disc across from you.
Now turn around and you will see a hallway to the right and left. Choose one, stand on the pressure plate and get through the course. If you fail, you can repeat each of the two courses, as long as you don't leave the area where the pressure plate is. This is a good thing, because getting this room to spawn is the biggest challenge.
Once you complete the first course (one has ice and cold, the other has thumper orbs), go across the main area to the other side and do the second course.
When you have completed both courses, go back to the laser and thumper orb room. Bunny hop your way up the pillar that has now risen toward the ceiling. Stand on top of the pillar and bullet jump into the room that takes you to the where you retrieve the drift mod.
Also, do not use syndicate weapons with an area of effect proc, or weapons like the Sonicor when you identify that the speed test room has appeared. These types of weapons can trigger the pressure plates prematurely and you can fail the test if this happens. I took a Braton Prime as my non-AOE weapon, and a Sonicor. There are reports of non-responsive exit wall discs. If you get glitched in one of the courses and the disc on the wall does not respond, a Sonicor or Ignis can get you out. Shoot at the wall and this can trigger the exit.