test(story): cover chapter ordering, display modes, and book paging

tests/int/story-beats.int.spec.ts

@@ -4,6 +4,8 @@ import config from "@/payload.config";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import type { StoryBeat, StoryBeatState, StoryVoiceover, User } from "@/payload-types";
 import { markBeatRead, setBeatReaction } from "@/lib/story";
+import { sortBeats, chronicleDisplayOrder } from "@/lib/story/sortBeats";
+import { bookColumnOffset, bookPageCount } from "@/lib/story/bookLayout";
 
 let payload: Payload;
 
@@ -469,3 +471,115 @@ describe("Story beats", () => {
     });
   });
 });
+
+describe("sortBeats (chapter ordering)", () => {
+  const baseBeat = {
+    status: "published" as const,
+    body: {} as StoryBeat["body"],
+  };
+
+  function beat(overrides: Partial<StoryBeat> & { id: number }): StoryBeat {
+    return { ...baseBeat, ...overrides } as unknown as StoryBeat;
+  }
+
+  it("defaults to real creation date ascending, ignoring in-story timestamps", () => {
+    // Fictional in-story dates deliberately out of release order.
+    const prologue = beat({
+      id: 1,
+      title: "Little Green Light",
+      createdAt: "2026-09-20T10:00:00Z",
+      occurredAt: new Date("2156-03-18T08:00:00Z").toISOString(),
+    });
+    const followUp = beat({
+      id: 2,
+      title: "What Makes Us Human",
+      createdAt: "2026-09-24T10:00:00Z",
+      occurredAt: new Date("2034-06-12T08:00:00Z").toISOString(),
+    });
+
+    const sorted = sortBeats([followUp, prologue]);
+    expect(sorted.map((beat) => beat.id)).toEqual([1, 2]);
+  });
+
+  it("puts explicitly ordered beats first, sorted by their order value", () => {
+    const old = beat({ id: 1, createdAt: "2026-01-01T00:00:00Z" });
+    const newer = beat({ id: 2, createdAt: "2026-02-01T00:00:00Z", order: 1 });
+    const pinnedLast = beat({ id: 3, createdAt: "2026-03-01T00:00:00Z", order: 2 });
+    // order = 0 is a valid curation value and must still lead the list.
+    const pinnedFirst = beat({ id: 4, createdAt: "2026-04-01T00:00:00Z", order: 0 });
+
+    const sorted = sortBeats([old, pinnedFirst, newer, pinnedLast]);
+    expect(sorted.map((beat) => beat.id)).toEqual([4, 2, 3, 1]);
+  });
+
+  it("does not mutate the input array", () => {
+    const a = beat({ id: 1, createdAt: "2026-01-01T00:00:00Z" });
+    const b = beat({ id: 2, createdAt: "2026-02-01T00:00:00Z" });
+    const input = [b, a];
+
+    sortBeats(input);
+    expect(input.map((beat) => beat.id)).toEqual([2, 1]);
+  });
+});
+
+describe("chronicleDisplayOrder (page display)", () => {
+  const baseBeat = {
+    status: "published" as const,
+    body: {} as StoryBeat["body"],
+  };
+
+  function beat(overrides: Partial<StoryBeat> & { id: number }): StoryBeat {
+    return { ...baseBeat, ...overrides } as unknown as StoryBeat;
+  }
+
+  it("shows the newest chapter first by default, with chapter numbers still ascending", () => {
+    const ch1 = beat({ id: 1, createdAt: "2026-09-20T10:00:00Z" });
+    const ch2 = beat({ id: 2, createdAt: "2026-09-21T10:00:00Z" });
+    const ch3 = beat({ id: 3, createdAt: "2026-09-22T10:00:00Z" });
+
+    const { beats, chapterById } = chronicleDisplayOrder([ch1, ch2, ch3]);
+
+    expect(beats.map((beat) => beat.id)).toEqual([3, 2, 1]);
+    expect(chapterById.get(1)).toBe(1);
+    expect(chapterById.get(2)).toBe(2);
+    expect(chapterById.get(3)).toBe(3);
+  });
+
+  it("switches to book mode when any beat is hand-ordered", () => {
+    const a = beat({ id: 1, createdAt: "2026-09-20T10:00:00Z" });
+    const b = beat({ id: 2, createdAt: "2026-09-21T10:00:00Z" });
+    const c = beat({ id: 3, createdAt: "2026-09-22T10:00:00Z", order: 1 });
+
+    const { beats, chapterById } = chronicleDisplayOrder([a, b, c]);
+
+    expect(beats.map((beat) => beat.id)).toEqual([3, 1, 2]);
+    expect(chapterById.get(3)).toBe(1);
+  });
+});
+
+describe("bookLayout (Book view paging)", () => {
+  it("counts one page when content fits the viewport", () => {
+    // One 2-up page: scrollWidth = column width = (1200 - 32) / 2 = 584.
+    expect(bookPageCount(584, 1200, 2)).toBe(1);
+    // scrollWidth == viewport width means both visible pages are exactly full: 2 pages.
+    expect(bookPageCount(1200, 1200, 2)).toBe(2);
+  });
+
+  it("counts pages from the measured multicol scrollWidth", () => {
+    // 3 pages at 2-up: scrollWidth = 3 * pitch - gap = 3 * 616 - 32 = 1816.
+    expect(bookPageCount(1816, 1200, 2)).toBe(3);
+    // A lone right page (2.5 pages of content) still counts as its own page.
+    expect(bookPageCount(1816 + 300, 1200, 2)).toBe(4);
+  });
+
+  it("pays the gap once per page in single-column mode", () => {
+    // 2 pages at 1-up, viewport 700: scrollWidth = 2 * 732 - 32 = 1432.
+    expect(bookPageCount(1432, 700, 1)).toBe(2);
+  });
+
+  it("computes the flip offset as pageIndex * pitch", () => {
+    expect(bookColumnOffset(0, 1200, 2)).toBe(0);
+    expect(bookColumnOffset(2, 1200, 2)).toBe(1232);
+    expect(bookColumnOffset(1, 700, 1)).toBe(732);
+  });
+});