Executing the game without render

I would like to run tests for levels, and for that purpose, I'd like a single level to be able to run instantaneously.

Given how my game is developed, it should be possible. All I want to do is skipping all the rendering parts and only have my 'Update' callbacks called.

My goal is to have a set of inputs, along with the time of their execution in 'normal' game time. I want to stretch the time as I please to have the 'normal' game time shrinked to perhaps a couple of seconds, and compute how the level would finish with that given set of input.

The goal is to determine a path that the player can follow to win the level, and be able to confirm after each modification of the level that this path is still valid, that the player won't die if he follows it.

This might be possible if I could trigger myself the execution of all the Update callback, or skip any other callbacks. Any suggestion ?