The practice test is a room accessed via the Sandbox. This is the only room that is always open upon every visit to the Sandbox. It does not contain any formal tests; rather it is used to test various loadouts against 5 non-aggressive Creeps. These enemies respawn upon defeat in a random location around the room. There is also an Access Point that allows Red to adjust her loadout for testing.
While in the practice test, a scoreboard appears in the upper left corner of the screen. This scoreboard lists the total damage done by the player's last Turn() within the practice test, as well as the player's record for damage done during a single Turn() within the practice test.
There are two achievements related to the Practice Test: Anything() and Everything(). These achievements require the player to do 1024 and 2048 damage in a single Turn() within the practice test. Players can unlock both achievements at once by doing more than 2048 damage in a single Turn().