Information Technology Reference
In-Depth Information
under permissible operating conditions. A system which informs the user as to why
the data failed is more robust than a product that crashes whenever the data is
slightly deviated.
10.5.4 Performance
Performance is another aspect of the product that must be tested. It is essential to
know the extent to which the product meets its constraints with regard to response
time or space requirements. Real-time software is characterized by hard time
constraints, that is, time constraints of such a nature that is a constraint is not met,
information is lost. With all real-time systems, the performance must meet every
time constraint listed in the specification.
10.5.5 Correctness
Correctness is satisfied if the output specifications of a product are satisfied. In
other words, if input that satisfies the input specifications provided and the product
is given all the resources it needs, then the product is correct if the output satisfies
the output specifications. This also has worrisome implications. Suppose the
product is tested against a broad variety of test data. Does this mean that the
product is acceptable?
Unfortunately, it does not. If a product is correct, all that means is that it
satisfies the specifications. What if specifications themselves are incorrect? After
all, the correctness of a product is meaningless if its specifications are incorrect.
The fact that a product is correct is not sufficient because the specifications in
terms of which it was shown to be correct may be wrong. With all the difficulties
associated with execution-based testing, computer scientists have tried to come up
with other ways of ensuring that a product does what it is supposed to do.
10.5.6 Usability Testing
Especially useful for web application testing, usability testing is important for
determining how easy the interface of a system makes it on the user, i.e. how well
does the interface guide the user in a timely and consistent manner (Pressman
2005
). In order to test usability, Pressman discusses a sequence of steps:
1. Define testing categories and goals
2. Design tests to evaluate each goal
3. Select participants
