Requirements

Vocabulary

English	Meaning
requirements engineering	Finding, analysing, agreeing and managing what a software system must provide.
functional requirement	A statement of a behaviour or service the system must provide.
non-functional requirement	A constraint or quality requirement, such as response time, availability or security.
use case	A description of interactions by which an actor achieves a goal using a system.

What and how well

Requirements engineering: a functional requirement says what the system does ("a member can borrow up to 5 books"); a non-functional requirement says how well ("search answers within 2 s"). A use case walks one goal end to end with its actors.

{exercise:uni-cs1201-kinds}

Practice

Search answers within 2 seconds is —

Difficulty 1/5 · 100 coins + a small bonus on first completion today

"Easy to use" cannot fail a test. "A new member completes first borrow in under 3 minutes without help (measured with 5 first-time users)" — now pass/fail exists.
The course list: FR-1 limit 5 (sixth borrow rejected); FR-2 due = date + 21; FR-3 one reminder per overdue day; NFR-1 search p95 under 2 s on 10 000 titles. Each maps to an acceptance test by name.

{exercise:uni-cs1201-testable}

Practice

A requirement is testable when —

Difficulty 1/5 · 100 coins + a small bonus on first completion today

Requirement $\to$ acceptance test $\to$ red test $\to$ next commit's reason: the chain is auditable — a commit that closes FR-2 says so.
Watch for the mistakes: solution inside requirements ("use Redis" — the need, not the means); unmeasurable adjectives; silent assumptions (the 21-day period is a named constant, not folklore).

{exercise:uni-cs1201-trace}

Practice

A commit that closes FR-2 must say so because —

Difficulty 1/5 · 100 coins + a small bonus on first completion today