Quality scenarios document required quality attributes. They help to describe required or desired qualities of a system, in pragmatic and informal manner, yet making the abstract notion of “quality” concrete and tangible.

A practical approach to describe quality requirement is the (open-source) arc42 quality model, which contains more than 75 specific examples of quality requirements.

• Event/stimulus: Any condition or event arriving at the system
• System (or part of the system) is stimulated by the event.
• Response: The activity undertaken after the arrival of the stimulus.
• Metric (response measure): The response should be measurable in some fashion.

There are different kinds of scenarios:

1. Usage scenarios: The system is used (any use case or system function is executed). Such scenarios describe how the system behaves in these cases, e.g. in terms of runtime performance, memory consumption, throughput or similar.
2. Change (or modification) scenarios: Any component within the system, its environment or its operational infrastructure changes or is being changed.
3. Failure scenarios: Some part of the system, its infrastructure or neighbors fail.