Preconditions

The CRA.core.preconditions assembly / packgage is a component developed to make numeric tests of pre-conditions and post-conditions in clients of different types. This component was developed having as main target software components implementing agro-ecological models. In fact, pre-conditions and post-conditions are not only useful, when tested, to get all the advantages in software development of the design-by-contract approach, but they are also an essential part of model documentation. Furthermore, the clear definition of pre-conditions and post-conditions is of great help during the development of agro-ecological model components; in fact, it allows the programmer to more easily define unit tests by narrowing the ranges of inputs and outputs to be tested. This component can also be used for form inputs validation in applications with a graphical user interface.
A top requirement for the design of this component was to make its use in clients as simple as possible. As a side effect, the information passed from the client to the component might be, in some cases, slightly redundant, but we believe this is widely compensated by its ease of use. The component provides some output options for showing/storing tests results (screen, txt file, XML file), but its design also allows clients to easily define custom outputs.