fix: blocks not receiving their own delete events

core/block.ts

@@ -20,6 +20,7 @@ import './events/events_block_create.js';
 import './events/events_block_delete.js';
 
 import {Blocks} from './blocks.js';
+import {BlockDelete} from './events/events_block_delete.js';
 import type {Comment} from './comment.js';
 import * as common from './common.js';
 import {Connection} from './connection.js';
@@ -330,10 +331,6 @@ export class Block implements IASTNodeLocation, IDeletable {
       eventUtils.fire(new (eventUtils.get(eventUtils.BLOCK_DELETE))(this));
     }
 
-    if (this.onchangeWrapper_) {
-      this.workspace.removeChangeListener(this.onchangeWrapper_);
-    }
-
     eventUtils.disable();
 
     try {
@@ -1027,7 +1024,13 @@ export class Block implements IASTNodeLocation, IDeletable {
       this.workspace.removeChangeListener(this.onchangeWrapper_);
     }
     this.onchange = onchangeFn;
-    this.onchangeWrapper_ = onchangeFn.bind(this);
+    this.onchangeWrapper_ = (e) => {
+      onchangeFn.call(this, e);
+      if (e.type === eventUtils.BLOCK_DELETE &&
+          (e as BlockDelete).blockId === this.id) {
+        this.workspace.removeChangeListener(this.onchangeWrapper_!);
+      }
+    };
     this.workspace.addChangeListener(this.onchangeWrapper_);
   }
 

tests/mocha/event_block_delete_test.js

@@ -12,7 +12,8 @@ import {sharedTestSetup, sharedTestTeardown} from './test_helpers/setup_teardown
 
 suite('Block Delete Event', function() {
   setup(function() {
-    sharedTestSetup.call(this);
+    const {clock} = sharedTestSetup.call(this, {fireEventsNow: false});
+    this.clock = clock;
     defineRowBlock();
     this.workspace = new Blockly.Workspace();
   });
@@ -22,20 +23,23 @@ suite('Block Delete Event', function() {
   });
 
   suite('Receiving', function() {
-    test('blocks receive their own delete events', function() {
+    test('blocks receive their own delete events', function(done) {
       Blockly.Blocks['test'] = {
-        onchange: function(e) {},
+        onchange: function(e) { },
       };
       // Need to stub the definition, because the property on the definition is
       // what gets registered as an event listener.
       const spy = sinon.spy(Blockly.Blocks['test'], 'onchange');
       const testBlock = this.workspace.newBlock('test');
 
       testBlock.dispose();
+      this.clock.tick(2);  // Fire events. The built-in timeout is 0.
 
       const deleteClass = eventUtils.get(eventUtils.BLOCK_DELETE);
-      chai.assert.isTrue(spy.calledOnce);
-      chai.assert.isTrue(spy.getCall(0).args[0] instanceof deleteClass);
+      chai.assert.isTrue(
+          spy.calledWith(sinon.match.instanceOf(deleteClass)),
+          'Expected the block to receive its own delete event.');
+      done();
     });
   });
 

tests/mocha/test_helpers/setup_teardown.js

@@ -105,6 +105,8 @@ function wrapDefineBlocksWithJsonArrayWithCleanup_(sharedCleanupObj) {
  *
  * @param {Object<string, boolean>} options Options to enable/disable setup
  *    of certain stubs.
+ * @return {{clock: *}} The fake clock (as part of an object to make refactoring
+ *     easier).
  */
 export function sharedTestSetup(options = {}) {
   this.sharedSetupCalled_ = true;
@@ -122,6 +124,9 @@ export function sharedTestSetup(options = {}) {
   this.blockTypesCleanup_ = this.sharedCleanup.blockTypesCleanup_;
   this.messagesCleanup_ = this.sharedCleanup.messagesCleanup_;
   wrapDefineBlocksWithJsonArrayWithCleanup_(this.sharedCleanup);
+  return {
+    clock: this.clock,
+  };
 }
 
 /**