evidence-binder/src/visual-guide/rect-registry.test.ts

/**
 * Rect registry unit tests — exercise every public surface plus the
 * §7-contract guarantees:
 *   - register/unregister fire subscriber events
 *   - getRect returns the live result of the registered callback
 *   - invalidate fires a global `rect-changed` event
 *   - version bumps on every emit
 *   - re-registering the same (kind,id) supersedes the prior callback;
 *     the stale unregister cleanup does not delete the new entry.
 */

import { describe, expect, it } from "vitest";

import {
  createRectRegistry,
  type RectRegistryEvent,
} from "./rect-registry";

function fakeRect(x: number, y: number, w: number, h: number): DOMRect {
  // happy-dom/jsdom isn't loaded for this test — synth a DOMRect-shaped
  // object. The registry contract only reads these properties.
  return {
    x,
    y,
    width: w,
    height: h,
    top: y,
    left: x,
    right: x + w,
    bottom: y + h,
    toJSON() {
      return { x, y, width: w, height: h };
    },
  } as DOMRect;
}

describe("createRectRegistry", () => {
  it("returns null for unknown rects", () => {
    const r = createRectRegistry();
    expect(r.getRect("field", "missing")).toBeNull();
  });

  it("register/getRect roundtrip", () => {
    const r = createRectRegistry();
    r.register("field", "f1", () => fakeRect(1, 2, 3, 4));
    const rect = r.getRect("field", "f1");
    expect(rect).not.toBeNull();
    expect(rect!.x).toBe(1);
    expect(rect!.width).toBe(3);
  });

  it("getRect reflects live callback results", () => {
    const r = createRectRegistry();
    let xPos = 10;
    r.register("highlight", "h1", () => fakeRect(xPos, 0, 5, 5));
    expect(r.getRect("highlight", "h1")!.x).toBe(10);
    xPos = 200;
    expect(r.getRect("highlight", "h1")!.x).toBe(200);
  });

  it("returns null when the callback throws", () => {
    const r = createRectRegistry();
    r.register("field", "boom", () => {
      throw new Error("nope");
    });
    expect(r.getRect("field", "boom")).toBeNull();
  });

  it("emits registered + unregistered events", () => {
    const r = createRectRegistry();
    const events: RectRegistryEvent[] = [];
    r.subscribe((e) => events.push(e));
    const unregister = r.register("evidence-card", "ev1", () => fakeRect(0, 0, 1, 1));
    unregister();
    expect(events).toEqual([
      { type: "registered", kind: "evidence-card", id: "ev1" },
      { type: "unregistered", kind: "evidence-card", id: "ev1" },
    ]);
  });

  it("invalidate emits a global rect-changed event and bumps version", () => {
    const r = createRectRegistry();
    const events: RectRegistryEvent[] = [];
    r.subscribe((e) => events.push(e));
    const before = r.getVersion();
    r.invalidate();
    expect(events).toEqual([{ type: "rect-changed" }]);
    expect(r.getVersion()).toBe(before + 1);
  });

  it("re-registering the same (kind,id) supersedes; stale cleanup is a no-op", () => {
    const r = createRectRegistry();
    const events: RectRegistryEvent[] = [];
    r.subscribe((e) => events.push(e));

    const firstGetRect = () => fakeRect(1, 1, 1, 1);
    const secondGetRect = () => fakeRect(9, 9, 9, 9);

    const cleanup1 = r.register("highlight", "x", firstGetRect);
    r.register("highlight", "x", secondGetRect); // supersede

    // The stale cleanup must not remove the new registration.
    cleanup1();

    expect(r.getRect("highlight", "x")!.x).toBe(9);
    // Two `registered` events, no `unregistered` event — the second
    // register overwrote without an explicit unregister, and the stale
    // cleanup detected the (kind,id) holds a different callback.
    expect(events.filter((e) => e.type === "unregistered")).toHaveLength(0);
    expect(events.filter((e) => e.type === "registered")).toHaveLength(2);
  });

  it("subscribe returns an unsubscribe that detaches the listener", () => {
    const r = createRectRegistry();
    let count = 0;
    const off = r.subscribe(() => count++);
    r.invalidate();
    off();
    r.invalidate();
    expect(count).toBe(1);
  });

  it("listener errors do not break sibling listeners", () => {
    const r = createRectRegistry();
    let okCount = 0;
    r.subscribe(() => {
      throw new Error("boom");
    });
    r.subscribe(() => {
      okCount++;
    });
    r.invalidate();
    expect(okCount).toBe(1);
  });

  it("list enumerates current registrations", () => {
    const r = createRectRegistry();
    r.register("field", "f1", () => null);
    r.register("evidence-card", "ev1", () => null);
    r.register("highlight", "h1", () => null);
    const list = r.list();
    expect(list).toHaveLength(3);
    expect(list).toEqual(
      expect.arrayContaining([
        { kind: "field", id: "f1" },
        { kind: "evidence-card", id: "ev1" },
        { kind: "highlight", id: "h1" },
      ]),
    );
  });
});