2 Why We Need Model-Based Testing

206 Testing Systems with Complex State
Transition coverage. Another widely used notion of behavioral coverage is to
visit all the different transitions of the state machine. You can implement a
transition coverage function as follows. It is useful to map states to their hash
codes here, rather than keeping around full states.
Bag GetTransitionCoverage(IState s, Action a)
{
return new Bag(Term.Create("Cp",
new Literal(s.GetHashCode()),a));
}
Notice that it is not necessary to compute the actual target state of the
transition, because it is uniquely determined by the source state and the action,
and would therefore not affect the coverage.
12.4.2 Action selection
Our custom strategy derives from the basic strategy. It takes a given model program
model and a given coverage function getCoverage.
partial class CustomStrategy : Strategy
{
CoverageFunction GetCoverage;
}
public CustomStrategy(ModelProgram model,
{
}
this.GetCoverage = getCoverage;
CoverageFunction getCoverage) : base(model)
The custom strategy uses a history variable coveragePoints, which also happens
to be a bag, that keeps count of the total number of occurrences of all the coverage
points seen so far. Initially the bag is empty.
partial class CustomStrategy
{
Bag coveragePoints = Bag.EmptyBag;
}
The main purpose of the custom strategy is to provide a particular implementation
of the method SelectAction. The idea is that an action is selected in such a way
that its reward is maximized. The GetReward function is defined below. If there are
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