Harry Bevan

1. 01 · Requirement

   The user story

   As a visitor, I want to start the car myself, so the intro never plays without me and I stay in control of it.

   Acceptance criteria

   • AC1START only works once the safety guard is lifted, and lowering the guard disarms it.
   • AC2Pressing START runs the sequence once: five red lights, all green, then the lap.
   • AC3“Skip intro” is the first focusable element and goes straight to the content, with focus on the hero.
   • AC4Everything works with a keyboard alone.
   • AC5With reduced motion, the sequence uses fades only and ends in the same place.
   • AC6No sound plays before the visitor’s first click, and muting is remembered.
   • AC7A finished intro is remembered for the session, and “Replay start” runs it again.

2. 02 · Analysis

   States, risks and techniques

   States

   intro → armed → starting → track

   • intro → armed (lift the guard)
   • armed → intro (lower the guard)
   • armed → starting → track (press START)
   • any stage → track (Skip intro)
   • track → intro (Replay start)

   Risks

   • An accidental or repeated start
   • Keyboard focus lost or trapped
   • Motion that makes visitors unwell
   • Audio playing without consent
   • Content hidden if something fails

   Techniques

   • State transition
   • Negative testing
   • Equivalence partitioning (input methods)
   • Accessibility
   • Cross-device

3. 03 · Test cases

   14 prioritised test cases

   9 P1 · 5 P2 · each with its technique and the Playwright test that automates it

   See all 14 test cases

   Test cases for the start sequence

   ID	Test case	Covers	Technique	Priority	Automated by
   TC-01	START is locked until the guard is lifted	AC1	Negative	P1	✓ guard then button reaches the track state
   TC-02	Lifting the guard arms START and announces it	AC1	State transition	P1	✓ guard then button reaches the track state
   TC-03	Lowering the guard disarms START again	AC1	State transition	P2	✓ the guard can be lowered again before starting
   TC-04	START runs five red lights, then green, then the lap	AC2	State transition	P1	✓ with sound on (the default), the sequence plays audio without errors
   TC-05	Pressing START again mid-sequence doesn’t restart it	AC2	Negative	P2	✓ pressing START again mid-sequence does not restart it
   TC-06	“Skip intro” is first in the tab order	AC3	Accessibility	P1	✓ initial screen: Skip intro is the first focusable element
   TC-07	“Skip intro” lands on the hero, with focus	AC3	State transition	P1	✓ Skip intro jumps straight to the track/hero state
   TC-08	Keyboard alone: Tab, Enter and Space complete the start	AC3, AC4	Equivalence partitioning	P1	✓ keyboard-only flow works end to end
   TC-09	No serious accessibility issues at any stage	AC3, AC4	Accessibility	P1	✓ start screen has no serious or critical violations✓ armed state has no serious or critical violations
   TC-10	Reduced motion: fades only, same end state, focus on the hero	AC5	Accessibility	P1	✓ shows the content without the full animation✓ Skip intro moves focus to the hero, not back onto the skip link
   TC-11	No audio exists before the first click	AC6	Negative	P1	✓ no audio is created and no AudioContext exists before any click
   TC-12	Muting is remembered after a reload	AC6	State transition	P2	✓ sound is on by default, and muting is remembered
   TC-13	A finished intro is skipped on reload; “Replay start” runs it again	AC7	State transition	P2	✓ completed intro is remembered for the session, and can be replayed
   TC-14	The whole start works on a phone-sized screen	AC1, AC2, AC3	Cross-device	P2	✓ guard then button reaches the track state (mobile Chromium)

4. 04 · Coverage

   Every criterion covered

   7/7 criteria covered ·14/14 test cases automated

   Which test cases cover each acceptance criterion

   Criterion	Covered by
   AC1 START only works once the safety guard is lifted, and lowering the guard disarms it.	TC-01, TC-02, TC-03, TC-14
   AC2 Pressing START runs the sequence once: five red lights, all green, then the lap.	TC-04, TC-05, TC-14
   AC3 “Skip intro” is the first focusable element and goes straight to the content, with focus on the hero.	TC-06, TC-07, TC-08, TC-09, TC-14
   AC4 Everything works with a keyboard alone.	TC-08, TC-09
   AC5 With reduced motion, the sequence uses fades only and ends in the same place.	TC-10
   AC6 No sound plays before the visitor’s first click, and muting is remembered.	TC-11, TC-12
   AC7 A finished intro is remembered for the session, and “Replay start” runs it again.	TC-13

   The matrix exposed one gap: nothing tested a second press of START mid-sequence. TC-05 was added, along with its Playwright test, which now runs on every deploy.

Demo: drafted by an AI agent from the requirement, then reviewed and edited by me, the way I’d run it on a real feature. The automated tests are this site’s own; their latest results are in the Telemetry panel above.