Dry run (testing)

A dry run (or a practice run) is a testing process where the effects of a possible failure are intentionally mitigated. For example, an aerospace company may conduct a "dry run" test of a jet's new pilot ejection seat while the jet is parked on the ground, rather than while it is in flight.
The usage of "dry run" in acceptance procedures (for example in the so-called FAT = factory acceptance testing) is meant as following: the factory — which is a subcontractor — must perform a complete test of the system it has to deliver "before" the actual acceptance by customer.
Etymology.
The term dry run appears to have originated from fire departments in the US. In order to practise, they would carry out dispatches of the fire brigade — known as "run"s — where water was not pumped — and which were therefore literally "dry". A "run" with real fire and water was referred to as a "wet run". The more general usage of the term seems to have arisen from widespread use by the US Armed Forces during World War II.