Definition

Testing carried out using no recognised test case design technique. Ad hoc testing is usually performed by component developers and is not documented. The tests do not have to be repeatable.

[Source: BCS+]

Comment

Ad hoc testing is a technique most commonly applied by developers prior to more formal component level tests and as such the tests are not often repeatable. Very often this is an efficient form of testing when software is being tested for the first time or a new release is made. The ad hoc testing is completed first, locating the obvious faults. Testers experienced in the system normally perform these ad hoc tests.

Organised tests are then either run in parallel or immediately following the ad hoc tests which ensure consistent test coverage and locate the more subtle faults.