From 8e7cb406f935f0f1a45dfcf57f41ca7dfbb16bef Mon Sep 17 00:00:00 2001
From: Monica Kozbial <6621618+moniika@users.noreply.github.com>
Date: Tue, 8 Jun 2021 12:28:59 -0700
Subject: [PATCH] Handle overriding components in ComponentManager (#4856)

---
 core/component_manager.js   | 12 +++++++++++-
 tests/mocha/toolbox_test.js |  6 ++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/core/component_manager.js b/core/component_manager.js
index 825473186..72828a4a4 100644
--- a/core/component_manager.js
+++ b/core/component_manager.js
@@ -54,9 +54,19 @@ Blockly.ComponentManager.ComponentDatum;
  * Adds a component.
  * @param {!Blockly.ComponentManager.ComponentDatum} componentInfo The data for
  *   the component to register.
+ * @param {boolean=} opt_allowOverrides True to prevent an error when overriding
+ *     an already registered item.
  * @template T
  */
-Blockly.ComponentManager.prototype.addComponent = function(componentInfo) {
+Blockly.ComponentManager.prototype.addComponent = function(
+    componentInfo, opt_allowOverrides) {
+  // Don't throw an error if opt_allowOverrides is true.
+  if (!opt_allowOverrides && this.componentData_[componentInfo.id]) {
+    throw Error(
+        'Plugin "' + componentInfo.id + '" with capabilities "' +
+        this.componentData_[componentInfo.id].capabilities +
+        '" already added.');
+  }
   this.componentData_[componentInfo.id] = componentInfo;
   for (var i = 0, type; (type = componentInfo.capabilities[i]); i++) {
     var typeKey = String(type).toLowerCase();
diff --git a/tests/mocha/toolbox_test.js b/tests/mocha/toolbox_test.js
index 19d88e4ab..ed49e7136 100644
--- a/tests/mocha/toolbox_test.js
+++ b/tests/mocha/toolbox_test.js
@@ -34,6 +34,8 @@ suite('Toolbox', function() {
     test('Init called -> Toolbox is subscribed to background and foreground colour', function() {
       var themeManager = this.toolbox.workspace_.getThemeManager();
       var themeManagerSpy = sinon.spy(themeManager, 'subscribe');
+      var componentManager = this.toolbox.workspace_.getComponentManager();
+      sinon.stub(componentManager, 'addComponent');
       this.toolbox.init();
       sinon.assert.calledWith(themeManagerSpy, this.toolbox.HtmlDiv,
           'toolboxBackgroundColour', 'background-color');
@@ -42,10 +44,14 @@ suite('Toolbox', function() {
     });
     test('Init called -> Render is called', function() {
       var renderSpy = sinon.spy(this.toolbox, 'render');
+      var componentManager = this.toolbox.workspace_.getComponentManager();
+      sinon.stub(componentManager, 'addComponent');
       this.toolbox.init();
       sinon.assert.calledOnce(renderSpy);
     });
     test('Init called -> Flyout is initialized', function() {
+      var componentManager = this.toolbox.workspace_.getComponentManager();
+      sinon.stub(componentManager, 'addComponent');
       this.toolbox.init();
       chai.assert.isDefined(this.toolbox.flyout_);
     });