From The Jargon File (version 4.4.7, 29 Dec 2003):
test
n.
1. Real users bashing on a prototype long enough to get thoroughly
acquainted with it, with careful monitoring and followup of the results.
2. Some bored random user trying a couple of the simpler features with a
developer looking over his or her shoulder, ready to pounce on mistakes.
Judging by the quality of most software, the second definition is far more
prevalent. See also demo.