feat: add chameleon test block

plugins/block-test/src/chameleon.js

@@ -0,0 +1,61 @@
+/**
+ * @license
+ * Copyright 2024 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+'use strict';
+
+/**
+ * @fileoverview Blocks that have both a previous connection and an output
+ *     connection while they are being dragged.
+ */
+
+import * as Blockly from 'blockly/core';
+
+Blockly.Blocks['test_chameleon'] = {
+  hasOutput: true,
+  hasPrevious: true,
+
+  init: function () {
+    this.appendDummyInput().appendField('chameleon');
+    this.setColour(120);
+    this.updateShape();
+  },
+
+  onchange: function (e) {
+    if (e.type === Blockly.Events.BLOCK_DRAG) {
+      console.log('got drag event');
+      this.hasPrevious =
+        !this.outputConnection || !this.outputConnection.targetBlock();
+      this.hasOutput = !this.getPreviousBlock();
+      this.updateShape();
+    }
+  },
+
+  updateShape: function () {
+    this.setPreviousStatement(this.hasPrevious);
+    this.setOutput(this.hasOutput);
+  },
+};
+
+/**
+ * The Chameleon Category.
+ */
+export const category = {
+  kind: 'CATEGORY',
+  name: 'Chameleon',
+  contents: [
+    {
+      kind: 'BLOCK',
+      type: 'test_chameleon',
+    },
+  ],
+};
+
+/**
+ * Initialize this toolbox category.
+ * @param {!Blockly.WorkspaceSvg} workspace The Blockly workspace.
+ */
+export function onInit(workspace) {
+  // NOP
+}

plugins/block-test/src/index.js

@@ -14,6 +14,10 @@ import * as Blockly from 'blockly/core';
 
 import {category as alignCategory, onInit as initAlign} from './align';
 import {category as basicCategory, onInit as initBasic} from './basic';
+import {
+  category as chameleonCategory,
+  onInit as initChameleon,
+} from './chameleon';
 import {
   category as connectionsCategory,
   onInit as initConnections,
@@ -34,6 +38,7 @@ export const toolboxTestBlocks = {
   contents: [
     alignCategory,
     basicCategory,
+    chameleonCategory,
     connectionsCategory,
     dragCategory,
     fieldsCategory,
@@ -50,6 +55,7 @@ export const toolboxTestBlocks = {
 export function toolboxTestBlocksInit(workspace) {
   initAlign(workspace);
   initBasic(workspace);
+  initChameleon(workspace);
   initConnections(workspace);
   initDrag(workspace);
   initFields(workspace);