When inspecting hydraulic brakes, you should pump the brake pedal three times then apply firm pressure to the pedal for five seconds. If the brakes are working well, the pedal should:

If the vehicle has hydraulic brakes, pump the brake pedal 3 times. Then apply firm pressure to the pedal and hold for 5 seconds. The pedal should not move. If it does, there may be a leak or other problem. Get it fixed before driving. [California Commercial Driver Handbook]