excalidraw/excalidraw-app/tests/collab.test.tsx

import { CaptureUpdateAction, newElementWith } from "@excalidraw/excalidraw";
import {
  createRedoAction,
  createUndoAction,
} from "@excalidraw/excalidraw/actions/actionHistory";
import { syncInvalidIndices } from "@excalidraw/element/fractionalIndex";
import { API } from "@excalidraw/excalidraw/tests/helpers/api";
import { act, render, waitFor } from "@excalidraw/excalidraw/tests/test-utils";
import { vi } from "vitest";

import ExcalidrawApp from "../App";

const { h } = window;

Object.defineProperty(window, "crypto", {
  value: {
    getRandomValues: (arr: number[]) =>
      arr.forEach((v, i) => (arr[i] = Math.floor(Math.random() * 256))),
    subtle: {
      generateKey: () => {},
      exportKey: () => ({ k: "sTdLvMC_M3V8_vGa3UVRDg" }),
    },
  },
});

vi.mock("../../excalidraw-app/data/firebase.ts", () => {
  const loadFromFirebase = async () => null;
  const saveToFirebase = () => {};
  const isSavedToFirebase = () => true;
  const loadFilesFromFirebase = async () => ({
    loadedFiles: [],
    erroredFiles: [],
  });
  const saveFilesToFirebase = async () => ({
    savedFiles: new Map(),
    erroredFiles: new Map(),
  });

  return {
    loadFromFirebase,
    saveToFirebase,
    isSavedToFirebase,
    loadFilesFromFirebase,
    saveFilesToFirebase,
  };
});

vi.mock("socket.io-client", () => {
  return {
    default: () => {
      return {
        close: () => {},
        on: () => {},
        once: () => {},
        off: () => {},
        emit: () => {},
      };
    },
  };
});

/**
 * These test would deserve to be extended by testing collab with (at least) two clients simultanouesly,
 * while having access to both scenes, appstates stores, histories and etc.
 * i.e. multiplayer history tests could be a good first candidate, as we could test both history stacks simultaneously.
 */
describe("collaboration", () => {
  it("should allow to undo / redo even on force-deleted elements", async () => {
    await render(<ExcalidrawApp />);
    const rect1Props = {
      type: "rectangle",
      id: "A",
      height: 200,
      width: 100,
    } as const;

    const rect2Props = {
      type: "rectangle",
      id: "B",
      width: 100,
      height: 200,
    } as const;

    const rect1 = API.createElement({ ...rect1Props });
    const rect2 = API.createElement({ ...rect2Props });

    API.updateScene({
      elements: syncInvalidIndices([rect1, rect2]),
      captureUpdate: CaptureUpdateAction.IMMEDIATELY,
    });

    API.updateScene({
      elements: syncInvalidIndices([
        rect1,
        newElementWith(h.elements[1], { isDeleted: true }),
      ]),
      captureUpdate: CaptureUpdateAction.IMMEDIATELY,
    });

    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(2);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
      expect(h.elements).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
    });

    // one form of force deletion happens when starting the collab, not to sync potentially sensitive data into the server
    window.collab.startCollaboration(null);

    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(2);
      // we never delete from the local snapshot as it is used for correct diff calculation
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
      expect(h.elements).toEqual([expect.objectContaining(rect1Props)]);
    });

    const undoAction = createUndoAction(h.history, h.store);
    act(() => h.app.actionManager.executeAction(undoAction));

    // with explicit undo (as addition) we expect our item to be restored from the snapshot!
    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(1);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false }),
      ]);
      expect(h.elements).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false }),
      ]);
    });

    // simulate force deleting the element remotely
    API.updateScene({
      elements: syncInvalidIndices([rect1]),
      captureUpdate: CaptureUpdateAction.NEVER,
    });

    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(1);
      expect(API.getRedoStack().length).toBe(1);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
      expect(h.elements).toEqual([expect.objectContaining(rect1Props)]);
    });

    const redoAction = createRedoAction(h.history, h.store);
    act(() => h.app.actionManager.executeAction(redoAction));

    // with explicit redo (as removal) we again restore the element from the snapshot!
    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(2);
      expect(API.getRedoStack().length).toBe(0);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
      expect(h.elements).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true }),
      ]);
    });

    act(() => h.app.actionManager.executeAction(undoAction));

    // simulate local update
    API.updateScene({
      elements: syncInvalidIndices([
        h.elements[0],
        newElementWith(h.elements[1], { x: 100 }),
      ]),
      captureUpdate: CaptureUpdateAction.IMMEDIATELY,
    });

    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(2);
      expect(API.getRedoStack().length).toBe(0);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false, x: 100 }),
      ]);
      expect(h.elements).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false, x: 100 }),
      ]);
    });

    act(() => h.app.actionManager.executeAction(undoAction));

    // we expect to iterate the stack to the first visible change
    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(1);
      expect(API.getRedoStack().length).toBe(1);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false, x: 0 }),
      ]);
      expect(h.elements).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: false, x: 0 }),
      ]);
    });

    // simulate force deleting the element remotely
    API.updateScene({
      elements: syncInvalidIndices([rect1]),
      captureUpdate: CaptureUpdateAction.NEVER,
    });

    // snapshot was correctly updated and marked the element as deleted
    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(1);
      expect(API.getRedoStack().length).toBe(1);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining(rect1Props),
        expect.objectContaining({ ...rect2Props, isDeleted: true, x: 0 }),
      ]);
      expect(h.elements).toEqual([expect.objectContaining(rect1Props)]);
    });

    act(() => h.app.actionManager.executeAction(redoAction));

    // with explicit redo (as update) we again restored the element from the snapshot!
    await waitFor(() => {
      expect(API.getUndoStack().length).toBe(2);
      expect(API.getRedoStack().length).toBe(0);
      expect(API.getSnapshot()).toEqual([
        expect.objectContaining({ id: "A", isDeleted: false }),
        expect.objectContaining({ id: "B", isDeleted: true, x: 100 }),
      ]);
      expect(h.history.isRedoStackEmpty).toBeTruthy();
      expect(h.elements).toEqual([
        expect.objectContaining({ id: "A", isDeleted: false }),
        expect.objectContaining({ id: "B", isDeleted: true, x: 100 }),
      ]);
    });
  });
});