If you "ace" a test, you have scored very highly. A fighter pilot who downs five or more enemy aircraft is called an ace. In some sports, the best team player at a given position is called their ace. An ace in tennis is a serve which the receiver is not even able to hit, winning the point in a single shot.

The slang word "aced" here indicates someone did quite well on the test. Perhaps the result was perfect.

Randy's answer is the correct definition for the sentence you provided. And to add to fdmaxey's list, "ace" can also mean the playing card with the A on it.

In a pack of playing cards, the Ace is the card with the highest value. So if Dave "aced the test", he scored top marks.

Ace - to get high scores from a test (high remarks on any endeavor)