Edge cases and transitions

Finds behavior gaps at input boundaries, interruptions and interactions between otherwise working features.

edge-cases-state-transitions

See how it helps

When is it useful?

Use when a happy-path test passes but real usage exposes unusual failures.

What does it help you do?

Exercises empty, extreme, malformed and boundary-value inputs.
Interrupts transitions through cancellation, navigation and repeated actions.
Checks recovery and cross-feature state combinations.

Try asking this

Test saving a form while permissions change and the user navigates away, preserving a clear final state. Delay the response until after navigation and access revocation. No success notice should claim a denied save, and the user should know whether edits survived.

Detailed documentation

Read the skill’s original instructions, examples and checks in their authored language.

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Edge Cases & State Transitions

Most production defects hide at the boundaries of data domains and in non-linear state transitions where users pause, go back, double-click, or lose connectivity.

Systematic Edge-Case Heuristics

Input & boundary value probing:
- Empty / null / whitespace: Empty strings "", whitespace-only " ", null, missing optional vs. required fields, empty arrays [].
- Zero, one, maximum, and overflow: 0, 1, maxAllowed, maxAllowed + 1, negative numbers, fractional values where integers are expected.
- Text & encoding extremes: Very long inputs, leading/trailing spaces, emojis, accented characters (őűáéíóöü), RTL text, HTML/Markdown/SQL/JSON special characters (< > & " ' \).
- Temporal boundaries: Midnight UTC vs. local timezone, DST transitions, leap days, expired tokens/invitations, past vs. future timestamps.
State-transition & interruption hazards:
- Double / rapid submission: Clicking Save, Submit, Start, or Delete twice in rapid succession before the first request resolves.
- Navigation & lifecycle interruptions: Browser Back/Forward buttons, page refresh (F5) mid-step, closing and reopening a modal, switching tabs or workspaces while an async request is in flight.
- Cancel -> Restart -> Resume: Aborting a running job or upload and immediately starting it again or viewing partial output.
- Stale / concurrent state: Acting on an item in Tab A after it was already edited, archived, cancelled, or deleted in Tab B.
Failure recovery & state rollback:
- Verify that when a save, transition, or external call fails:
  - The UI does not get stuck in an infinite spinner or disabled state.
  - User-entered form input is preserved so the user does not lose their work.
  - Partial database or local state is rolled back cleanly rather than leaving a half-created orphan record.
Cross-feature interactions:
- Check how the changed feature interacts with search/filtering, sorting, pagination, notifications, exports, and audit history.

Included files 1

SKILL.md