chore: Use JSON objects for context menu callbackFactory (#7382)

* chore: use json object for context callbackFactory

* Add test file for context menu callback function.

tests/mocha/contextmenu_test.js

@@ -0,0 +1,70 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  sharedTestSetup,
+  sharedTestTeardown,
+} from './test_helpers/setup_teardown.js';
+
+import {callbackFactory} from '../../build/src/core/contextmenu.js';
+import * as xmlUtils from '../../build/src/core/utils/xml.js';
+import * as Variables from '../../build/src/core/variables.js';
+
+suite('Context Menu', function () {
+  setup(function () {
+    sharedTestSetup.call(this);
+
+    // Creates a WorkspaceSVG
+    const toolbox = document.getElementById('toolbox-categories');
+    this.workspace = Blockly.inject('blocklyDiv', {toolbox: toolbox});
+  });
+
+  teardown(function () {
+    sharedTestTeardown.call(this);
+  });
+
+  suite('Callback Factory', function () {
+    setup(function () {
+      this.forLoopBlock = this.workspace.newBlock('controls_for');
+    });
+
+    test('callback with xml state creates block', function () {
+      const xmlField = Variables.generateVariableFieldDom(
+        this.forLoopBlock.getField('VAR').getVariable(),
+      );
+      const xmlBlock = xmlUtils.createElement('block');
+      xmlBlock.setAttribute('type', 'variables_get');
+      xmlBlock.appendChild(xmlField);
+
+      const callback = callbackFactory(this.forLoopBlock, xmlBlock);
+      const getVarBlock = callback();
+
+      chai.assert.equal(getVarBlock.type, 'variables_get');
+      chai.assert.equal(getVarBlock.workspace, this.forLoopBlock.workspace);
+      chai.assert.equal(
+        getVarBlock.getField('VAR').getVariable().getId(),
+        this.forLoopBlock.getField('VAR').getVariable().getId(),
+      );
+    });
+
+    test('callback with json state creates block', function () {
+      const jsonState = {
+        type: 'variables_get',
+        fields: {VAR: this.forLoopBlock.getField('VAR').saveState(true)},
+      };
+
+      const callback = callbackFactory(this.forLoopBlock, jsonState);
+      const getVarBlock = callback();
+
+      chai.assert.equal(getVarBlock.type, 'variables_get');
+      chai.assert.equal(getVarBlock.workspace, this.forLoopBlock.workspace);
+      chai.assert.equal(
+        getVarBlock.getField('VAR').getVariable().getId(),
+        this.forLoopBlock.getField('VAR').getVariable().getId(),
+      );
+    });
+  });
+});

tests/mocha/index.html

@@ -50,6 +50,7 @@
       import './connection_db_test.js';
       import './connection_test.js';
       import './contextmenu_items_test.js';
+      import './contextmenu_test.js';
       import './cursor_test.js';
       import './dropdowndiv_test.js';
       import './event_test.js';