[Matra et Alpine]

Didn't need a brake test,

he was unable to accelerate as without traction control he lost grip and came off the throttle. So the car didnt' accelerate as fast causing Lewis to run into him.

At least's what the lawyers will be saying

and you CAN "brake test" under accleration with the left foot But "brake test" is a term for any move where a leading driver will try to trick the following into panicking by being slower in unexpected places.