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228 Chapter 8 Software testing

8.4 User testing

User or customer testing is a stage in the testing process in which users or customers
provide input and advice on system testing. This may involve formally testing a sys-
tem that has been commissioned from an external supplier, or could be an informal
process where users experiment with a new software product to see if they like it and
that it does what they need. User testing is essential, even when comprehensive sys-
tem and release testing have been carried out. The reason for this is that influences
from the user’s working environment have a major effect on the reliability, perfor-
mance, usability, and robustness of a system.
It is practically impossible for a system developer to replicate the system’s work-
ing environment, as tests in the developer’s environment are inevitably artificial. For
example, a system that is intended for use in a hospital is used in a clinical environ-
ment where other things are going on, such as patient emergencies, conversations
with relatives, etc. These all affect the use of a system, but developers cannot include
them in their testing environment.
In practice, there are three different types of user testing:

1. Alpha testing, where users of the software work with the development team to
test the software at the developer’s site.
2. Beta testing, where a release of the software is made available to users to allow
them to experiment and to raise problems that they discover with the system
developers.

3. Acceptance testing, where customers test a system to decide whether or not it is
ready to be accepted from the system developers and deployed in the customer
environment.

In alpha testing, users and developers work together to test a system as it is being
developed. This means that the users can identify problems and issues that are not
readily apparent to the development testing team. Developers can only really work
from the requirements but these often do not reflect other factors that affect the prac-
tical use of the software. Users can therefore provide information about practice that
helps with the design of more realistic tests.
Alpha testing is often used when developing software products that are sold as
shrink-wrapped systems. Users of these products may be willing to get involved in
the alpha testing process because this gives them early information about new sys-
tem features that they can exploit. It also reduces the risk that unanticipated changes
to the software will have disruptive effects on their business. However, alpha testing
may also be used when custom software is being developed. Agile methods, such as
XP, advocate user involvement in the development process and that users should
play a key role in designing tests for the system.
Beta testing takes place when an early, sometimes unfinished, release of a soft-
ware system is made available to customers and users for evaluation. Beta testers