Game Development Reference
Expert Constructed Paths
Expert constructed paths are simply paths that a test or feature “expert�? traces based
on her knowledge of how the feature is likely to fail or where she needs to establish
confidence in a particular set of behaviors. They can be used by themselves or in com-
bination with the minimum or baseline strategies. Expert constructed paths do not
have to cover all of the flows in the diagram, nor do they have to be any minimum or
maximum length. The only constraint is that like all other paths they start at the IN
and end at the OUT.
Expert paths can be effective at finding problems when there is organizational mem-
ory of what has failed in the past or what new game functions are the most sensitive.
These paths may not have showed up at all in a path list generated by the minimum
or baseline criteria. The drawback of relying on this approach are the risks associated
with not covering every flow and the possibility of tester bias producing paths that do
not perform “unanticipated�? sequences of events.
Some expert constructed path strategies are
Repeat a certain flow or sequence of flows in combination with other path
Create paths that emphasize unusual or infrequent events
Create paths that emphasize critical or complex states
Create extremely long paths, repeating flows if necessary
Model paths after the most common ways the feature will be used
For example, the “emphasize critical or complex states�? strategy can be used for the
Ammo TFD in Figure 11.13. In this case, the HaveGun state will be emphasized. This
means that each path will pass through HaveGun at least once. It is also a goal to cover
all of the flows with this path set. To keep the paths short, head for the Exit flow once
the HaveGun state has been used.
One path that works is to go to HaveGun , try to shoot, and then leave. This path would
be 1, 2, 3, 4, 13. Another would incorporate the DropGun event in flow 7. The shortest
way out from there is via flow 9 followed by 13, resulting in the path 1, 2, 7, 9, 13. You
also need to include the two flows going into HaveGun from HaveGunHaveAmmo . This produces
the paths 1, 2, 4, 5, 4, 13 and 1, 2, 4, 6, 4, 13. Finish covering all of the flows, leaving
HaveGunHaveAmmo by using flow 8 in the path 1, 2, 4, 8, 9, 13.
All that remains are some slightly longer paths that cover the left side of the TFD.
Flows 1, 11, and 12 get you to HaveGunHaveAmmo . The quickest way from there to HaveGun
is either with flow 5 or 6. Choose flow 5, which results in the path 1, 11, 12, 5, 4, 13.