A brake test is a term used in motorsport. A driver is said to brake test another driver when the two are driving very close together and the front driver deliberately brakes very hard, causing the second driver to have to do likewise and often make an evasive maneuver to avoid an accident.
Because of the aggressive and dangerous nature of this move, a driver who makes such a move is often penalized. Penalties given for such actions can vary from time penalties, to exclusion from a race or event.
Brake test is commonly called a brake check in America. This may be a play on words based on a double meaning: checking the functionality of the brakes and reference to the hockey check.
References
Brake test Wikipedia(Text) CC BY-SA