6c5889c957
The alpha>0 guard never closed (each new tween re-captured the still- positive alpha), so DoorScene accumulated ~1 live tween per frame all night. Fade is now tween-free elapsedMs math with tests pinning that it reaches exactly 0 and stays there. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
41 lines
1.7 KiB
TypeScript
41 lines
1.7 KiB
TypeScript
import { describe, expect, it } from 'vitest';
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import { TUTORIAL_FADE_MS, TUTORIAL_MS, tutorialAlpha } from '../src/scenes/door/tutorialFade';
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// Regression guard for the door-tutorial fade. The original implementation was
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// `if (alpha > 0) tweens.add({ alpha: 0, duration: 800 })` inside update():
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// each frame's new tween re-captured the still-positive alpha, so the guard
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// never closed and DoorScene accumulated one live 800ms tween per frame
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// (~1,100 by the end of a night). The fade is now this pure function; these
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// tests pin the property that killed the tween version — it must actually
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// reach 0 and stay there.
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describe('tutorialAlpha', () => {
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it('holds at full alpha through the tutorial window', () => {
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expect(tutorialAlpha(0)).toBe(1);
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expect(tutorialAlpha(TUTORIAL_MS)).toBe(1);
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});
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it('fades linearly once the hold expires', () => {
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expect(tutorialAlpha(TUTORIAL_MS + TUTORIAL_FADE_MS / 2)).toBeCloseTo(0.5);
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expect(tutorialAlpha(TUTORIAL_MS + TUTORIAL_FADE_MS / 4)).toBeCloseTo(0.75);
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});
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it('reaches exactly 0 at fade end and never goes negative after', () => {
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expect(tutorialAlpha(TUTORIAL_MS + TUTORIAL_FADE_MS)).toBe(0);
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expect(tutorialAlpha(TUTORIAL_MS + TUTORIAL_FADE_MS + 1)).toBe(0);
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// A whole night later it is still pinned at 0 — the condition the old
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// tween-spawning guard could never satisfy.
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expect(tutorialAlpha(TUTORIAL_MS + 4 * 60 * 60 * 1000)).toBe(0);
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});
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it('is monotonically non-increasing frame over frame', () => {
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let prev = Infinity;
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for (let ms = 0; ms < TUTORIAL_MS + 2 * TUTORIAL_FADE_MS; ms += 16.67) {
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const a = tutorialAlpha(ms);
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expect(a).toBeLessThanOrEqual(prev);
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expect(a).toBeGreaterThanOrEqual(0);
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prev = a;
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}
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});
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});
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