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A central notion in XP is that design occurs both before and
after coding commences. Refactoring means that design occurs
continuously as the system is constructed. In fact, the
construction activity itself will provide the XP team with
guidance on how to improve the design.
c.
Coding
According to Pressman (2010:76), after stories are
developed and the preliminary design work is done, developers
do not move to code, but should design several unit tests that will
be used to exercise each of the stories that will be included in the
current release. Once the unit tests have been created, the
developer can focus on what must be implemented to pass the
test. Once the code is complete, it can be unit-tested immediately,
thereby providing instantaneous feedback to the developers.
The main concept during the coding activity is pair
programming. It is recommended that two people work together
at one computer workstation to create the code for a story. Pair
programming provides a mechanism for real-time problem
solving and real-time quality assurance (the code is reviewed as it
is created). It also keeps the developers focused on the problem at
hand.
After pair programmers finish their work, the code they
develop will be integrated with the work of others. In some cases
this is performed on a daily basis by an integration team. In other
cases, the pair programmers have integration responsibility. This
“continuous integration” strategy helps avoiding compatibility
and interfacing problems and provides a “smoke testing”
environment that helps to uncover errors early.
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