User Stories and Use Cases are both the important ways to effectively map the user requirement for the initial system mapping. Both work well as backlog items. They have some common properties that enable them to support the agile methodologies like kanban,scrum,specification by example and test-driven development. The answer to chose which under what circumstances lies in narrative given by Ivor Jacobson , that is for the user stories, selection can be carried out if there is easy access to subject matter experts and severity of errors is low.
Where as Use Cases and Use Case slices are more appropriate if you have no easy access to subject matter experts or the consequences of errors severity is very high. According to Jacobson use case approach can always scale down to the user stories.
In order to have better overview lets first look at some of the common terms that both the use cases and the user stories share .
Commonalities between Use Cases and User Stories:
- Ron Jofferies invented 03 Cs : Card , conversation and confirmation . Both of the User stories and use cases are place holders of a conversation and can benefit from these three Cs.
- Index cards can be used by both User stories and use cases slices to be written upon.
- Both can be further divided into smaller items or sliced up if they are too large.
- User stories and use cases slices , both define functionality slices which helps teams to accomplish in a sprint.
- User stories and use cases , both can be resulted into a test case that helps in establishing acceptance criteria.
- Planning poker is an estimation technique that can be used for the estimation of both User stories and use cases or use case slices.
Extra benefits you get from Use Cases :
Use cases and Use case slices both have some added advantages that they contribute , lets have a look at them:
- Both Use cases and Use case slices help in easier identification of the missing and redundant functionality
- Both Use cases and Use case slices, supports variety of systems ranging from simple , complex and systems of systems.
- Extent of the system and its value can be better grasped as both Use cases and Use case slices represents big picture in front of the people.
- understanding of system operations and how it performs is enhanced.
- Test Case generation and analysis is easy.
- On going Impact analysis is supported.
- Both Use cases and Use case slices provide the active scope management . It helps in establishing easy focus to provide viable minimal product.
- Test Assets are better organized,understood,maintained and applied .
- documentation is scale able and flexible. It helps in keeping the traceablity and contractual constraints.