Scenario

A scenario describes one specific behaviour of a product: a starting state, something that happens, and how the product responds. Scenarios aren't features, requirements, or test cases. They are statements of behaviour that anyone on the team can read and verify by using the product.

Each scenario has three parts: a Context (the situation), an Action (what triggers it), and an Outcome (how the product responds). Scenarios are grouped into three categories: happy path (the expected flow), edge case (unusual but valid situations that users often find surprising), and error (what happens when things go wrong).

Together, scenarios build up a complete picture of a feature's behaviour. A feature with only happy path scenarios leaves your support team unprepared for everything else. Good specifications cover edge cases and errors too, the places customers actually run into problems.