Test Planning and Management
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4.4 Life-Cycles and Four-Wheel-Drive Karmas
There is a large number of life-cycles around. You need to be aware of their strengths and weaknesses,
and the subtle ways they can (be used to) louse up projects. A fervent belief on a particular life-cycle
untrammeled by any concern for its weakness is an early danger sign in a project manager.
Remember that life-cycles only exist as models; they??™re simply attempts at describing what we do.
4.4.1 Who Cares about Process Models?
Life-cycle or process models are only useful in that they help us think about how we develop systems.
If we fail to have any process we get chaotic. If we have the wrong process we can at least rethink it.
In the end process models subtly influence thinking. What matters in any project is that the artefacts:
specifications, code, manuals, and tests get written, tested, and used.
4.4.2 The Waterfall Model
The waterfall [Royce] is the best known. It consists of 5 phases:
1. Requirements (in which the customer requirements are written).
2. Design (in which the high and low-level design documents are written).
3. Code (in which the code is written and (hopefully) unit tested).
4. System test (which is where we come in).
5. Installation and cutover: (in which the finished (!) system is installed, the users are trained, and
the system is put to use).
This is an approach which everyone says is out-of-date and which everyone uses more or less.
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