Duncan Tourolle
1836615dc0
- music landing: diverse per-genre album sliders (online counts / offline wide-probe fallback) and home-screen library shortcuts - add ArtistLinks component and shared navigation/genreDiversity utils - player/playback-mode refinements across Rust and frontend
80 lines
2.8 KiB
TypeScript
80 lines
2.8 KiB
TypeScript
import { describe, it, expect } from "vitest";
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import { selectDiverseGenres, sampleAcross } from "./genreDiversity";
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const g = (...names: string[]) => names.map(name => ({ name }));
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describe("sampleAcross", () => {
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it("returns input unchanged when at or under the count", () => {
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expect(sampleAcross([1, 2, 3], 5)).toEqual([1, 2, 3]);
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});
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it("spreads the sample across the whole list rather than taking a prefix", () => {
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// 26 letters, want ~7: a prefix would be A–G; striding spans A→Z.
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const letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".split("");
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const picked = sampleAcross(letters, 7);
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expect(picked[0]).toBe("A");
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// Reaches deep into the alphabet, not stuck near the front.
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expect(picked[picked.length - 1] >= "S").toBe(true);
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expect(picked.length).toBeLessThanOrEqual(7);
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});
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it("never exceeds the requested count", () => {
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const items = Array.from({ length: 100 }, (_, i) => i);
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expect(sampleAcross(items, 8).length).toBeLessThanOrEqual(8);
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});
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});
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describe("selectDiverseGenres", () => {
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it("returns input unchanged when at or under the limit", () => {
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const input = g("Rock", "Jazz");
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expect(selectDiverseGenres(input, 5)).toEqual(input);
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});
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it("seeds with the most populous genre (first in input)", () => {
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const out = selectDiverseGenres(g("Rock", "Jazz", "Hip Hop"), 1);
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expect(out.map(x => x.name)).toEqual(["Rock"]);
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});
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it("spreads the family instead of stacking near-synonyms", () => {
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// Count ranking puts all the Rock variants first; a naive top-N would
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// return four flavours of Rock. Diversity should pull in distinct genres.
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const input = g(
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"Rock",
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"Hard Rock",
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"Classic Rock",
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"Pop Rock",
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"Jazz",
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"Hip Hop",
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"Classical"
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);
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const names = selectDiverseGenres(input, 4).map(x => x.name);
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expect(names[0]).toBe("Rock"); // seeded by count
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expect(names).toContain("Jazz");
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expect(names).toContain("Hip Hop");
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expect(names).toContain("Classical");
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// Only the seed represents the Rock cluster.
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expect(names.filter(n => n.includes("Rock"))).toEqual(["Rock"]);
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});
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it("preserves count order as the tie-breaker among equally-distinct genres", () => {
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// All four are mutually distinct (no shared tokens), so every pick after
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// the seed is a distance tie and should follow input (count) order.
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const input = g("Rock", "Jazz", "Blues", "Folk");
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expect(selectDiverseGenres(input, 3).map(x => x.name)).toEqual([
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"Rock",
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"Jazz",
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"Blues",
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]);
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});
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it("is case- and separator-insensitive when comparing", () => {
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const input = g("Hip Hop", "hip-hop", "Reggae");
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// "Hip Hop" and "hip-hop" share all tokens → the second is redundant.
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expect(selectDiverseGenres(input, 2).map(x => x.name)).toEqual([
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"Hip Hop",
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"Reggae",
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]);
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});
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});
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