Agile practices: User Story


Describes functionality that will be valuable to a user of a system and composed of three aspects:

  • Card: a written description of the story used for planning and as a reminder
  • Conversation: verbal conversations about the story that serve to flesh out the details of the story
  • Confirmation: tests that convey and document details and that can be used to determine when a story is complete

Characteristics:

  • Indipendent: as much as possible (to prevent planning and estimation  problems due to story dependencies);
  • Negotiable: they are remainders for the team-customer conversation, details are written as notes (1 or 2 phrase). The challenge comes in learning to include just enough detail, other discussions become test (written on the rear of the card: “if I haven’t an account the application invite me to subscribe the service”);
  • Valuable: give value to the user, no use of technical details;
  • Estimable: it’s important the team is able to estimate. Common problems which block estimation: domain knowledge problem (solution: talk to product owner!), lack of technical knowledge (solution: realize a proof of concept), the story is too big (solution: find smaller constituent stories);
  • Small: too big or small stories are not suitable for planning (the burndown chart lose value and this prevent from project day-by-day status evaluation);
  • Testable: successfully passing its test prove that a story has been successfully developed and Done!.

Classic story statement template:

As a <role> I want to <what> So that <why>

Use Case versus User Story:

Use Case: Describes how an Actor interacts with the system to achieve a Goal
Focus is on user and validation – Tells a “complete story” with main flow and alternative flow (in case of error or different user behaviors).
User Story: A bite-size bit of functionality that has business value and can be developed in a few days.
Focus is on developer and production – Part of a “complete story”.

Tips:

  • Try to write independent stories to avoid story dependencies in priority evaluation;
  • Split stories when: developers say “too large”, cannot fit in one iteration, needs too much to do;
  • User story represents a team activity, so it could be of different kind: standard (standard user story), constraint (abstract non-functional story as “each password should be cipher on the database”), bug (if you consider the bugfixing in your development activity), technical (other time-consuming tasks, for example “install a new profiling tools”);
  • Cards are small to reduce verbosity, use the rear to best capture stories in the form of acceptance tests (“try with alphanumeric input”, “try miss name field”, …);
  • Check the story doesn’t contain technical jergon;
  • If you need to release an excluded story inside the current iteration, you can: change priority, split a big story and exclude its less-priority part, reduce the scope of other stories.

Non-functional requirements:

We can consider some of these as standalone stories (password expiration, …) but others have to be written in a Non Functional Requirements Guideline document (password encryption on database, general validation rules, …) shared with the team. However we must try to remember and express some of these as Acceptance Test during the discussion.

Documentation tasks:

Effort for write/update documents with a relationship with a specific user story (e.g. functional document, …) must be included in the story estimation.

Effort for cross-stories documents (installation guides, …) must be considered in a separate story (e.g. a “As Operation I want an installation guide so that I can install”) and have specific estimation.

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