The test feature you talk about is already in the new game. While your building, click on the test button. The train will appear as a white outline and run the course till the point at which you are currently constructing. It won't crash when it gets to that point either, it'll just keep on cycling. Very helpful when building coasters so you know how fast the train is/isn't going through the elements you've laid out. :)
This ain't no book you can close, when the big light hits your eyes. Cropduster-Riot Act-Pearl Jam