Try to replicate an issue mentioned by matsuyama

loro-checkout-test.ts

import { describe, expect, it } from "vitest";
import { LoroDoc, UndoManager } from "../bundler/index";

describe("Reproduction", () => {
  it("checkout after snapshot import", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.import(snapshot);

    // Try to checkout to v0
    doc2.checkout(v0);

    expect(doc2.toJSON()).toStrictEqual({
      text: "H",
    });
  });

  it("checkout after snapshot import with different peer", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.setPeerId(1n);
    doc2.import(snapshot);

    // Try to checkout to v0
    doc2.checkout(v0);

    expect(doc2.toJSON()).toStrictEqual({
      text: "H",
    });
  });

  it("checkout after fromSnapshot", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = LoroDoc.fromSnapshot(snapshot);

    // Try to checkout to v0
    doc2.checkout(v0);

    expect(doc2.toJSON()).toStrictEqual({
      text: "H",
    });
  });

  it("checkout with rich text", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "Hello");
    text.mark({ start: 0, end: 5 }, "bold", true);
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(5, " World");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.import(snapshot);

    doc2.checkout(v0);

    expect(doc2.toJSON()).toStrictEqual({
      text: "Hello",
    });
  });

  it("checkout with subscription", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.import(snapshot);

    let eventTriggered = false;
    doc2.subscribe((e) => {
      eventTriggered = true;
      expect(e.by).toBe("checkout");
    });

    doc2.checkout(v0);
    expect(eventTriggered).toBe(true);
  });

  it("checkout with undo manager", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    const undoManager = new UndoManager(doc, {});

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.import(snapshot);

    const undoManager2 = new UndoManager(doc2, {});

    doc2.checkout(v0);

    expect(doc2.toJSON()).toStrictEqual({
      text: "H",
    });
  });

  it("checkout event inspection", () => {
    const doc = new LoroDoc();
    doc.setPeerId(0n);
    const text = doc.getText("text");
    text.insert(0, "H");
    doc.commit();
    const v0 = doc.frontiers();

    text.insert(1, "i");
    doc.commit();

    const snapshot = doc.export({ mode: "snapshot" });

    const doc2 = new LoroDoc();
    doc2.import(snapshot);

    doc2.subscribe((e) => {
      if (e.by === "checkout") {
        expect(e.events.length).toBeGreaterThan(0);
      }
    });

    doc2.checkout(v0);
  });
});