siftlode/frontend/src/lib/feedSort.yt.test.ts

import { describe, it, expect } from "vitest";
import { feedSortOptions, sortYtResults, YT_SORT_KEYS, SORT_KEYS } from "./feedSort";
import type { Video } from "./api";

// The live-YouTube results view shipped with no sort control at all: the provider's order was the
// only order, "már 1 lapnyi találatnál is lenne értelme". These pin what the added control means —
// it reorders the page already on screen, and it only offers keys a search result actually carries.
const v = (over: Partial<Video>): Video => ({ id: over.title ?? "?", ...over }) as Video;
const titles = (list: Video[]) => list.map((x) => x.title);

const RESULTS: Video[] = [
  v({
    title: "b-old-short",
    published_at: "2019-01-01T00:00:00Z",
    view_count: 10,
    duration_seconds: 60,
  }),
  v({
    title: "a-new-long",
    published_at: "2026-01-01T00:00:00Z",
    view_count: 5,
    duration_seconds: 6000,
  }),
  v({
    title: "c-mid-mid",
    published_at: "2022-01-01T00:00:00Z",
    view_count: 99,
    duration_seconds: 600,
  }),
];

describe("YT_SORT_KEYS", () => {
  it("offers only keys a live search result can be ordered by", () => {
    // `subscribers`/`priority` describe a SUBSCRIPTION, which a search hit is not, and `shuffle` on a
    // ranked result list is noise. An option that cannot mean anything here is worse than no option.
    expect(YT_SORT_KEYS).not.toContain("subscribers");
    expect(YT_SORT_KEYS).not.toContain("priority");
    expect(YT_SORT_KEYS).not.toContain("shuffle");
    // …and every key it does offer is part of the feed's one vocabulary, not a private spelling.
    for (const k of YT_SORT_KEYS) {
      if (k === "relevance") continue; // the provider's ranking; not in the wire-sort map
      expect(SORT_KEYS).toContain(k);
    }
  });
});

describe("sortYtResults", () => {
  it("leaves the provider's ranking alone on `relevance`", () => {
    expect(titles(sortYtResults(RESULTS, "relevance", "desc", "en"))).toEqual([
      "b-old-short",
      "a-new-long",
      "c-mid-mid",
    ]);
  });

  it("orders by upload date in both directions", () => {
    expect(titles(sortYtResults(RESULTS, "date", "desc", "en"))).toEqual([
      "a-new-long",
      "c-mid-mid",
      "b-old-short",
    ]);
    expect(titles(sortYtResults(RESULTS, "date", "asc", "en"))).toEqual([
      "b-old-short",
      "c-mid-mid",
      "a-new-long",
    ]);
  });

  it("orders by views and by length", () => {
    expect(titles(sortYtResults(RESULTS, "popular", "desc", "en"))[0]).toBe("c-mid-mid");
    expect(titles(sortYtResults(RESULTS, "duration", "desc", "en"))[0]).toBe("a-new-long");
    expect(titles(sortYtResults(RESULTS, "duration", "asc", "en"))[0]).toBe("b-old-short");
  });

  it("orders by title alphabetically, not by code point", () => {
    const accented = [v({ title: "Zebra" }), v({ title: "Ábel" }), v({ title: "alma" })];
    expect(titles(sortYtResults(accented, "title", "asc", "en"))).toEqual([
      "Ábel",
      "alma",
      "Zebra",
    ]);
  });

  it("sinks results with no value to the END in both directions", () => {
    // YouTube does not always report a duration; "unknown" is not "the shortest".
    const mixed = [
      v({ title: "unknown", duration_seconds: null }),
      v({ title: "long", duration_seconds: 900 }),
      v({ title: "short", duration_seconds: 60 }),
    ];
    expect(titles(sortYtResults(mixed, "duration", "desc", "en"))).toEqual([
      "long",
      "short",
      "unknown",
    ]);
    expect(titles(sortYtResults(mixed, "duration", "asc", "en"))).toEqual([
      "short",
      "long",
      "unknown",
    ]);
  });

  it("keeps the provider's ranking inside a tie, in both directions", () => {
    // Flipping the direction must reverse the RANKING, not shuffle equally-ranked hits around.
    const tied = [
      v({ title: "first", view_count: 100 }),
      v({ title: "second", view_count: 100 }),
      v({ title: "third", view_count: 5 }),
    ];
    expect(titles(sortYtResults(tied, "popular", "desc", "en"))).toEqual([
      "first",
      "second",
      "third",
    ]);
    expect(titles(sortYtResults(tied, "popular", "asc", "en"))).toEqual([
      "third",
      "first",
      "second",
    ]);
  });

  it("does not reorder anything for a key it cannot honour", () => {
    // A pref stored before this view offered a control can name `shuffle` or `priority`.
    expect(titles(sortYtResults(RESULTS, "priority", "desc", "en"))).toEqual(titles(RESULTS));
    expect(titles(sortYtResults(RESULTS, "shuffle", "desc", "en"))).toEqual(titles(RESULTS));
  });

  it("does not mutate the array it was given", () => {
    const input = [...RESULTS];
    sortYtResults(input, "date", "asc", "en");
    expect(titles(input)).toEqual(titles(RESULTS));
  });
});

describe("feedSortOptions", () => {
  // The library feed and the live results used to build their options from two copies of this
  // mapping; one helper means a key cannot get a different default direction in one of the modes.
  it("gives directional keys their default direction and marks shuffle/relevance directionless", () => {
    // Literal directions, not the implementation's own table: comparing against that table let a
    // wrong entry in it pass. Name is the one key that starts ascending.
    const opts = feedSortOptions(
      ["relevance", "date", "duration", "title", "shuffle"],
      (k) => `label:${k}`,
    );
    expect(opts.map((o) => [o.key, o.label, !!o.directionless, o.defaultDir])).toEqual([
      ["relevance", "label:relevance", true, undefined],
      ["date", "label:date", false, "desc"],
      ["duration", "label:duration", false, "desc"],
      ["title", "label:title", false, "asc"],
      ["shuffle", "label:shuffle", true, undefined],
    ]);
  });
});