fix bug in unapply for batch command

cypress/integration/unit/history.js

@@ -20,11 +20,17 @@ describe('history', function () {
   // const svg = document.createElementNS(NS.SVG, 'svg');
   let undoMgr = null;
 
-  class MockCommand {
-    constructor (optText) { this.text_ = optText; }
-    apply () { /* */ } // eslint-disable-line class-methods-use-this
-    unapply () { /* */ } // eslint-disable-line class-methods-use-this
-    getText () { return this.text_; }
+  class MockCommand extends hstory.Command {
+    constructor (optText) {
+      super();
+      this.text = optText;
+    }
+    apply (handler) {
+      super.apply(handler, () => { /* */ });
+    }
+    unapply (handler) {
+      super.unapply(handler, () => { /* */ });
+    }
     elements () { return []; } // eslint-disable-line class-methods-use-this
   }
 
@@ -482,17 +488,17 @@ describe('history', function () {
 
   it('Test BatchCommand', function () {
     let concatResult = '';
-    MockCommand.prototype.apply = function () { concatResult += this.text_; };
+    MockCommand.prototype.apply = function (handler) { concatResult += this.text; };
 
     const batch = new hstory.BatchCommand();
     assert.ok(batch.unapply);
     assert.ok(batch.apply);
     assert.ok(batch.addSubCommand);
     assert.ok(batch.isEmpty);
-    assert.equal(typeof batch.unapply, typeof function () { /* */ });
-    assert.equal(typeof batch.apply, typeof function () { /* */ });
-    assert.equal(typeof batch.addSubCommand, typeof function () { /* */ });
-    assert.equal(typeof batch.isEmpty, typeof function () { /* */ });
+    assert.equal(typeof batch.unapply, 'function');
+    assert.equal(typeof batch.apply, 'function');
+    assert.equal(typeof batch.addSubCommand, 'function');
+    assert.equal(typeof batch.isEmpty, 'function');
 
     assert.ok(batch.isEmpty());
 
@@ -506,8 +512,9 @@ describe('history', function () {
     assert.equal(concatResult, 'abc');
 
     MockCommand.prototype.apply = function () { /* */ };
-    MockCommand.prototype.unapply = function () { concatResult += this.text_; };
+    MockCommand.prototype.unapply = function () { concatResult += this.text; };
     concatResult = '';
+    assert.ok(!concatResult);
     batch.unapply();
     assert.equal(concatResult, 'cba');
 

src/svgcanvas/history.js

@@ -22,7 +22,7 @@ export const HistoryEventTypes = {
 /**
 * Base class for commands.
 */
-class Command {
+export class Command {
   /**
   * @returns {string}
   */
@@ -434,7 +434,7 @@ export class BatchCommand extends Command {
   */
   unapply (handler) {
     super.unapply(handler, () => {
-      this.stack.forEach((stackItem) => {
+      this.stack.reverse().forEach((stackItem) => {
         console.assert(stackItem, 'stack item should not be null');
         stackItem && stackItem.unapply(handler);
       });