fix(blocks): destroy the Tool of a Block that leaves the collection

src/components/blocks.ts

@@ -200,6 +200,7 @@ export default class Blocks {
     if (replace) {
       this.blocks[index].holder.remove();
       this.blocks[index].call(BlockToolAPI.REMOVED);
+      this.blocks[index].destroy();
     }
 
     const deleteCount = replace ? 1 : 0;
@@ -237,6 +238,8 @@ export default class Blocks {
     prevBlock.holder.replaceWith(block.holder);
 
     this.blocks[index] = block;
+
+    prevBlock.destroy();
   }
 
   /**
@@ -291,6 +294,8 @@ export default class Blocks {
 
     this.blocks[index].call(BlockToolAPI.REMOVED);
 
+    this.blocks[index].destroy();
+
     this.blocks.splice(index, 1);
   }
 
@@ -300,7 +305,10 @@ export default class Blocks {
   public removeAll(): void {
     this.workingArea.innerHTML = '';
 
-    this.blocks.forEach((block) => block.call(BlockToolAPI.REMOVED));
+    this.blocks.forEach((block) => {
+      block.call(BlockToolAPI.REMOVED);
+      block.destroy();
+    });
 
     this.blocks.length = 0;
   }

src/components/modules/blockManager.ts

@@ -534,7 +534,6 @@ export default class BlockManager extends Module {
       }
 
       this._blocks.remove(index);
-      block.destroy();
 
       /**
        * Force call of didMutated event on Block removal

test/cypress/tests/api/blocks.cy.ts

@@ -221,6 +221,55 @@ describe('api.blocks', () => {
   /**
    * api.blocks.insert(type, data, config, index, needToFocus, replace, id)
    */
+  /**
+   * api.blocks.update() swaps the Block in the collection, so the Tool of the
+   * replaced Block has to be destroyed — otherwise it leaks.
+   */
+  describe('.update() cleanup', () => {
+    it('should destroy the Tool of the Block it replaces', () => {
+      const onDestroy = cy.spy().as('onDestroy');
+
+      /**
+       * Mock of Tool that reports its destruction
+       */
+      class DestroyableTool extends ToolMock {
+        /**
+         * Called by the editor when the Block leaves the collection
+         */
+        public destroy(): void {
+          onDestroy();
+        }
+      }
+
+      const existingBlock = {
+        id: 'destroyable-id-1',
+        type: 'destroyableTool',
+        data: {
+          text: 'Some text',
+        },
+      };
+
+      cy.createEditor({
+        tools: {
+          destroyableTool: {
+            class: DestroyableTool,
+          },
+        },
+        data: {
+          blocks: [
+            existingBlock,
+          ],
+        },
+      }).then((editor) => {
+        editor.blocks.update(existingBlock.id, { text: 'Updated text' });
+
+        cy.wait(100).then(() => {
+          cy.get('@onDestroy').should('have.been.calledOnce');
+        });
+      });
+    });
+  });
+
   describe('.insert()', function () {
     it('should preserve block id if it is passed', function () {
       cy.createEditor({