Concept
Prototype the uncertain part instead of specifying it by imagination
Some ambiguity should be tested, not polished into a longer specification.
When it fits
- The team cannot write credible acceptance criteria because the solution or user interaction is still genuinely uncertain.
When to avoid it
- Prototype code and demo success are not production evidence for security, reliability, performance or maintainability unless those were deliberately tested.
The idea
Identify the uncertainty and build the cheapest prototype that can answer it: sketch, mock, sample data flow, throwaway code or technical spike. State what the prototype is testing and what production qualities it intentionally does not prove. Use the result to revise the requirement.
An example
Before specifying a complex approval UI, the team tests two clickable flows with likely users; before choosing an integration library, it runs a spike against the real API limits.
Check your result
The prototype has a question it can answer and an explicit boundary on what its success does not prove.
Keep this limit in mind
- Prototype code and demo success are not production evidence for security, reliability, performance or maintainability unless those were deliberately tested.
Connected ideas
AlternativeWrite acceptance evidence before implementation starts
Evidence and sources
GOV.UK user-story guidance recommends recording the actor, needed action and goal, focusing on why the need exists, and using acceptance criteria to state observable outcomes that show the job is done.
User-story syntax is one framing method and is not appropriate for every technical, regulatory or infrastructure requirement.
Writing user stories · What to include; Focus on the goal; Acceptance criteria
GOV.UK prototyping guidance recommends exploring and testing alternative designs before committing to production and notes that prototype code may deliberately not meet production standards.
A prototype reduces selected uncertainties; it does not prove production reliability, security, accessibility or scalability unless those properties are explicitly tested.
Making prototypes · When to use prototypes; Using code prototypes