Use Cases writing Tips

Use Case Definition:

" A Use case us the specification of a set of actions performed by a system, which yields an observable result that is, typically, of value for one or more actors or other stake holders of the system (UML 2) "

TIPS:

• A Use Case is the story of how the business or System and the user interact.
• Use Cases are formal requirements that clearly define the resultant value.
• Use Cases transform "shall" statements into groups that provide observable value and context, organized from a user prospective.
•  Use Cases describe both functionality and results.
• A common mistake is to consider requirements with design specifications.
• Diagrams provide a visual reference for the use case.
• People are the most important use case element.
• Establishing a use case style makes writing and reading them faster and easier.
• Use Cases should have a single main flow and multiple alternative flows.
• Alternative flows explain deviation from the main flow.
• Use Cases are not design documents they are requirement documents.
• References define the beginning and the end of an alternative flow.
• References indicate what caused an alternative flow to start and what the system does in response.
• Readability can suffer if there are "if statements" in a flow, because it usually means multiple requirements.
• Selecting a single choice for an actor, and creating alternative flows for other choices, can simplify the main flow.
• A poorly written use case has too many create, read, update and delete activities, reducing clarity.
• Removing CRUD creates a simpler document.
• Sequencing the events in a flow is not always necessary to achieve clarity.
• Don't forget you are writing use cases for the end user.
• Agreement on use cases structure and processes is essential to achieving quality and consistency.

Ref: Tips for writing good use cases by James Heumann