element-web/test/unit-tests/editor/history-test.ts

/*
Copyright 2024 New Vector Ltd.
Copyright 2019 The Matrix.org Foundation C.I.C.

SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE files in the repository root for full details.
*/

import HistoryManager, { IHistory, MAX_STEP_LENGTH } from "../../../src/editor/history";
import EditorModel from "../../../src/editor/model";
import DocumentPosition from "../../../src/editor/position";

describe("editor/history", function () {
    it("push, then undo", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        const caret1 = new DocumentPosition(0, 0);
        const result1 = history.tryPush(model, caret1, "insertText", {});
        expect(result1).toEqual(true);
        parts[0] = "hello world";
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        expect(history.canUndo()).toEqual(true);
        const undoState = history.undo(model) as IHistory;
        expect(undoState.caret).toBe(caret1);
        expect(undoState.parts).toEqual(["hello"]);
        expect(history.canUndo()).toEqual(false);
    });
    it("push, undo, then redo", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        parts[0] = "hello world";
        const caret2 = new DocumentPosition(0, 0);
        history.tryPush(model, caret2, "insertText", {});
        history.undo(model);
        expect(history.canRedo()).toEqual(true);
        const redoState = history.redo() as IHistory;
        expect(redoState.caret).toBe(caret2);
        expect(redoState.parts).toEqual(["hello world"]);
        expect(history.canRedo()).toEqual(false);
        expect(history.canUndo()).toEqual(true);
    });
    it("push, undo, push, ensure you can`t redo", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        parts[0] = "hello world";
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        history.undo(model);
        parts[0] = "hello world!!";
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        expect(history.canRedo()).toEqual(false);
    });
    it("not every keystroke stores a history step", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        const firstCaret = new DocumentPosition(0, 0);
        history.tryPush(model, firstCaret, "insertText", {});
        const diff = { added: "o" };
        let keystrokeCount = 0;
        do {
            parts[0] = parts[0] + diff.added;
            keystrokeCount += 1;
        } while (!history.tryPush(model, new DocumentPosition(0, 0), "insertText", diff));
        const undoState = history.undo(model) as IHistory;
        expect(undoState.caret).toBe(firstCaret);
        expect(undoState.parts).toEqual(["hello"]);
        expect(history.canUndo()).toEqual(false);
        expect(keystrokeCount).toEqual(MAX_STEP_LENGTH + 1); // +1 before we type before checking
    });
    it("history step is added at word boundary", function () {
        const history = new HistoryManager();
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        const parts = ["h"];
        let diff = { added: "h" };
        const blankCaret = new DocumentPosition(0, 0);
        expect(history.tryPush(model, blankCaret, "insertText", diff)).toEqual(false);
        diff = { added: "i" };
        parts[0] = "hi";
        expect(history.tryPush(model, blankCaret, "insertText", diff)).toEqual(false);
        diff = { added: " " };
        parts[0] = "hi ";
        const spaceCaret = new DocumentPosition(1, 1);
        expect(history.tryPush(model, spaceCaret, "insertText", diff)).toEqual(true);
        diff = { added: "y" };
        parts[0] = "hi y";
        expect(history.tryPush(model, blankCaret, "insertText", diff)).toEqual(false);
        diff = { added: "o" };
        parts[0] = "hi yo";
        expect(history.tryPush(model, blankCaret, "insertText", diff)).toEqual(false);
        diff = { added: "u" };
        parts[0] = "hi you";

        expect(history.canUndo()).toEqual(true);
        const undoResult = history.undo(model) as IHistory;
        expect(undoResult.caret).toEqual(spaceCaret);
        expect(undoResult.parts).toEqual(["hi "]);
    });
    it("keystroke that didn't add a step can undo", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        const firstCaret = new DocumentPosition(0, 0);
        history.tryPush(model, firstCaret, "insertText", {});
        parts[0] = "helloo";
        const result = history.tryPush(model, new DocumentPosition(0, 0), "insertText", { added: "o" });
        expect(result).toEqual(false);
        expect(history.canUndo()).toEqual(true);
        const undoState = history.undo(model) as IHistory;
        expect(undoState.caret).toEqual(firstCaret);
        expect(undoState.parts).toEqual(["hello"]);
    });
    it("undo after keystroke that didn't add a step is able to redo", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        history.tryPush(model, new DocumentPosition(0, 0), "insertText", {});
        parts[0] = "helloo";
        const caret = new DocumentPosition(1, 1);
        history.tryPush(model, caret, "insertText", { added: "o" });
        history.undo(model);
        expect(history.canRedo()).toEqual(true);
        const redoState = history.redo() as IHistory;
        expect(redoState.caret).toBe(caret);
        expect(redoState.parts).toEqual(["helloo"]);
    });

    it("overwriting text always stores a step", function () {
        const history = new HistoryManager();
        const parts = ["hello"];
        const model = { serializeParts: () => parts.slice() } as unknown as EditorModel;
        const firstCaret = new DocumentPosition(0, 0);
        history.tryPush(model, firstCaret, "insertText", {});
        const diff = { at: 1, added: "a", removed: "e" };
        const secondCaret = new DocumentPosition(1, 1);
        const result = history.tryPush(model, secondCaret, "insertText", diff);
        expect(result).toEqual(true);
    });
});