2 Why We Need Model-Based Testing

Systems with Complex State 205
if (content.Contains(element))
{
Execute.AddCoveragePoint("in the bag")
content = content.Remove(element);
}
else
Execute.AddCoveragePoint("not in the bag")
}
You can define a method GetCoveragePoints in your custom strategy as
follows. (A concrete example of a custom strategy definition is shown in the
next section.) It is assumed here that the strategy has a field called model
that references a given model program. The reserved name for getting all the
coverage points that are covered by executing an annotated action from a given
state is "CoveragePoints".
Bag GetCoveragePoints(IState s, Action a)
{
Bag cps;
model.GetTargetState(s, a, "CoveragePoints", out cps);
return cps;
}
Note that the target state of the transition is irrelevant in this context; only
the bag of all the coverage points that were covered is relevant and is returned.
Action coverage. If you only care about covering the different actions, independent
of the start state, then you can use the following coverage function. If the
actions take no arguments then this coverage function is equivalent to the first
one above.
Bag GetActionCoverage(IState s, Action a)
{ return new Bag(a); }
State coverage. A widely used notion of behavioral coverage is to visit all the
different states of the state machine. You can implement a state coverage
function as follows. It is useful to map states to their hash codes here, rather
than keeping around full states as coverage points.
Bag GetStateCoverage(IState s, Action a)
{
int stateHash = model.GetTargetState(s, a).GetHashCode();
return new Bag(new Literal(stateHash));
}
more free ebooks download links at:
http://www.ebook-x.com