tips for writing good use cases

Writing good use cases is more of an art than a science.

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 perspective.

Use cases describe both functionality and results.

A common mistake is to confuse requirements with design specifications.

Diagrams provide a visual reference for the use cases.

People are the most important use case element.

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 requirements documents.

Reference define the beginning and the end of an alternative flow.

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.