The parachute for the Mars Science Laboratory (with the Curiosity rover) was tested in the NASA Ames Research Center 80 by 120 Foot Wind Tunnel.
The wind tunnel is currently capable of air speeds up to 100 knots (190 km/h; 120 mph). But how was the parachute tested with a speed and pressure similar to a real entry to Mars? Only by scaling speed and air viscosity or by using a smaller model parachute instead of the original size?
Picture and speed data from Wikipedia.