Avoid Overuse of State Variables

State variables are an advanced modeling concept which enables use of a simple, explicit concept of “state” in a world of activity diagrams where state is only implicit in a control flow. It is intended to be used to keep track of “what has happened before” – similar to the “memory” concept in electronic calculators. Overuse of state variables, e.g., create and managing a lot of them in parallel makes models hard to follow. In particular, in large models it is easy to overlook proper setting of state variables in all flow branches and it gets difficult to find the root cause for unexpected test generation results. A good indicator for overuse of state variables is when you start getting increasingly confronted with variable initialization warnings in the Problems View of the Conformiq Modeling perspective.

To reduce your use of state variables restructure your control flows and manage state by reducing the amount of explicit and implicit merge nodes in your control flows.

Another common use of state variables is to parameterize or influence selection of paths in a (very generic) sub diagram. This practice can easily backfire and create situations where it will never be possible to reach 100% coverage with default target settings, e.g., by calling a subactivity diagram with the state variable always and only set to one value and the sub activity having flows covering multiple settings. Note that expert users can remedy this situation by manually setting all the test targets related to sub activity diagram in Test Targets view of the Conformiq Test Generation perspective to “DON’T_CARE” (see “Review Testing Target Settings before Analyzing Your Model”).