UML Weekend Crash Course™ - To Parent Directory

Session 8—Identifying the Use Case Scenarios 91
The result of completing the description of all the scenarios should be a reasonably complete
test plan for each Use Case. Remember, though, that you have only modeled the system
at the Use Case level. That means that the test plan you have so far is really only
acceptance-level testing, not full system or integration testing. But the Use Case level test
plan provides the framework for all the test plans for successive phases in the project.
REVIEW
Use Cases express what the users expect the system to provide.
Use Case narratives explain in detail how the users expect to interact with the system
when they invoke the Use Case.
Scenarios break down the narrative explanation to provide a detailed examination
of every possible outcome of the Use Case, why each outcome happens, and how the
system is supposed to respond.
The Activity diagram provides a visual evaluation of the Use Case narrative.
Although it isn’t necessary to use an Activity diagram, it can be very helpful, especially
for complex Use Cases.
A scenario is a single logical path through a Use Case, expressing one possible outcome.
Finding Use Case scenarios requires you to follow each unique series of activities
and decisions from the beginning of the Use Case to a single end point.
Together, the scenarios should account for every possible way that a Use Case could
execute.
When the scenarios have been identified, they may be used to develop a comprehensive
acceptance-level test plan. They may also be used to test the results of subsequent
analysis and design efforts.
QUIZ YOURSELF
1. What is a Use Case scenario (See “Describing Use Case Scenarios.”)
2. How many scenarios are in a Use Case (See “Describing Use Case Scenarios.”)
3. What two methods can you use to describe the logical flow of a Use Case (See
“Describing Use Case Scenarios” and “How to find Use Case scenarios.”)
4. If a scenario is a single logical path, how do you handle looping logic (See
“Applying Use Case scenarios.”)
5. How will the scenarios be used later in the project (See “Applying Use Case
scenarios.”)