“INVEST in good stories”
The INVEST acronym simply summarises what a good user story would look like.
- Independent – As much as possible, user stories must be independent from one another. Their concept or purpose should not overlap.
- Negotiable – A user story is an invitation to a conversation, not a contract. It should capture the essence of what the user desires, and should be able to take changes as it gets refined further.
- Valuable – A good user story should be valuable to the specified user, and its benefit should be clearly stated in the “so that” clause.
- Estimable – Estimates are tools for negotiating the scope or acceptance criteria and splitting big user stories to smaller user stories. A user story should be clear enough for the Scrum team to estimate its size or complexity.
- Small – Because Scrum teams work in Sprints, a user story must be small or granular enough to fit within the agreed time-box.
- Testable – In order for the user story to be developed and tested, it must be clear enough to everyone. Understanding what the user story is about allows testers to write and execute good tests for it.
Going back to US-001, here are a few reasons why it doesn’t meet the INVEST criteria:
- Not valuable enough – “Easy registration process” can mean different things to different users. More research needs to be done to determine what “easy” is for their users.
- Not small enough – A typical end-to-end registration process would include clicking on registration link, filling out details, possibly correcting form mistakes, and confirming the email address. Based on those function points, US-001 needs to be split into several user stories.
- Not testable enough – Because the benefits are not clear and the user story could be split further, scope for development and testing are not clear as well.
It’s possible to set US-001 as an epic for smaller user stories, since it’s a big story that could over-arch several features. For the purpose of a demonstration, let’s say that we’ve written the following as one of the user stories under US-001:
US-002 – As a new user registering to the website, I want to know if my input fields are correct or incorrect before I submit the form so that I can save time and avoid re-entering data.
This new user story has focused in on one of the earlier concerns on correcting mistakes. It also clearly stated who the user is and what they want in particular. It could still be negotiated and revised, but that will depend on the Scrum team during product backlog refinement or sprint planning.
The INVEST criteria helps determine when a user story is granular enough and ready for implementation. Testers can help with further the clarification of user stories by using their mindset and experience in listing their acceptance criteria.
Recommended Further Reading
The following materials may assist you in order to get the most out of this course: