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Component and store cases for everything in this series, several of which exist because the thing they pin is invisible everywhere else: - `view-lifecycle` and `keyboard-reach` — a document listener count that does not grow across a simulated navigate cycle, and a tab sequence that reaches the sidebar and plays a row without a mouse. - `notifications`, `notification-store`, `confirm-dialog`, `empty-states` — the four levels, the (level, region, key) coalescing window, and loading/failed/empty as three states. - `card-grid-repaint` — fails if `artists-view`'s or `genres-view`'s per-render arrow functions are hoisted to stable fields, which is the audit's own recommendation and takes the cards from 1 highlighted to 0. It exists for no other reason. - `lazy-track-details` — reads the five sources and fails on a returning static import, the same shape as `TestNoDirectRuntimeEmits` and for the same reason: the invariant is about what the code does *not* say. - `now-playing` — a position report that changes nothing must not touch the DOM again, and a track change must. The first fails against the old unconditional `updated()`. - `playlist-virtualization`, `list-render-cost`, `selection`, `icons`, and the store cases for the library-filter race, the never-settling waiter and the per-playlist patch.
79 lines
2.4 KiB
TypeScript
79 lines
2.4 KiB
TypeScript
/**
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* `perf.M7`/`M8`: the two Explore art caches were unbounded on a view
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* that never unmounts. Measured at twelve searches, a session retained
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* **8.48 MB** and was still climbing 0.7 MB per search, because a cover
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* thumbnail is a ~27 kB base64 data URL and an artist photo is ~128 kB.
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*
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* `LRUMap` is the bound. The behaviours below are the ones the call
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* sites actually depend on — in particular that a *read* is what keeps
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* an entry alive, since the entry being rendered must never be the one
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* evicted, and that `has()` is not a read, because both caches use
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* `has()` to test a negative "already tried, no art" marker.
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*/
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import { describe, expect, it } from 'vitest';
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import { LRUMap } from '@utils/lru-map';
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describe('LRUMap', () => {
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it('behaves like a Map below its cap', () => {
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const m = new LRUMap<string, number>(4);
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m.set('a', 1).set('b', 2);
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expect([m.get('a'), m.get('b'), m.get('c'), m.size]).toEqual([
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1, 2, undefined, 2,
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]);
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});
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it('never exceeds its cap', () => {
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const m = new LRUMap<number, number>(10);
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for (let i = 0; i < 1000; i++) m.set(i, i);
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expect(m.size).toBe(10);
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});
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it('evicts the oldest entry first', () => {
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const m = new LRUMap<string, number>(2);
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m.set('a', 1).set('b', 2).set('c', 3);
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expect([m.get('a'), m.get('b'), m.get('c')]).toEqual([undefined, 2, 3]);
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});
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it('a read renews an entry, so the rendered one survives', () => {
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const m = new LRUMap<string, number>(2);
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m.set('a', 1).set('b', 2);
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m.get('a');
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m.set('c', 3);
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// 'b' was the least recently *used*, even though 'a' was older.
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expect([m.get('a'), m.get('b'), m.get('c')]).toEqual([1, undefined, 3]);
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});
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it('has() does not renew, so a negative marker cannot outrank real art', () => {
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const m = new LRUMap<string, string>(2);
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// '' is the "already attempted, no art" marker both caches store.
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m.set('miss', '').set('art', 'data:…');
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m.has('miss');
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m.set('new', 'data:…');
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expect(m.has('miss')).toBe(false);
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expect(m.get('art')).toBe('data:…');
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});
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it('overwriting an existing key does not grow the map or evict', () => {
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const m = new LRUMap<string, number>(2);
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m.set('a', 1).set('b', 2).set('a', 99);
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expect([m.size, m.get('a'), m.get('b')]).toEqual([2, 99, 2]);
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});
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it('rejects a cap that cannot hold anything', () => {
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expect(() => new LRUMap<string, number>(0)).toThrow(/at least 1/);
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});
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});
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