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

/*
Copyright 2019 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

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);
    });
});