Possible fix for the error asserting issue

lib/ember-test-helpers/test-module-for-component.js

@@ -238,6 +238,14 @@ export function setupComponentIntegrationTest() {
       outletState = { render: stateToRender, outlets: {} };
     }
 
+    // A hacky fix for the issue https://github.com/emberjs/ember.js/issues/15013 — listen
+    // for errors on the global window object and save them in order to rethrow later.
+    var uncaughtErrors = [];
+    var originalOnErrorHandler = window.onerror;
+    window.onerror = function windowErrorsHandler(error) {
+      uncaughtErrors.push(error);
+    };
+
     Ember.run(() => {
       toplevelView.setOutletState(outletState);
     });
@@ -247,6 +255,16 @@ export function setupComponentIntegrationTest() {
       hasRendered = true;
     }
 
+    if (uncaughtErrors.length > 0) {
+      // Rethrow any errors caught on the window to a test framework after the component
+      // was rendered:
+      uncaughtErrors.forEach(function throwWindowError(error) {
+        throw error;
+      });
+    }
+    // Restore global onerror handler:
+    window.onerror = originalOnErrorHandler;
+
     // ensure the element is based on the wrapping toplevel view
     // Ember still wraps the main application template with a
     // normal tagged view

tests/test-module-for-component-test.js

@@ -62,6 +62,22 @@ var ChangingColor = Ember.Component.extend({
   }
 });
 
+// A component which throws an error during render:
+var BadComponent = Ember.Component.extend({
+  layout: Ember.Handlebars.compile('<input type="text" onfocus={{action "focus"}}>'),
+  didInsertElement() {
+    this.set('input', this.element.querySelector('input'));
+  },
+  didRender() {
+    this.get('input').focus();
+  },
+  actions: {
+    focus() {
+      this.get('unexistedMethod')();
+    }
+  }
+});
+
 function setupRegistry() {
   setResolverRegistry({
     'component:x-foo': Ember.Component.extend(),
@@ -373,7 +389,8 @@ moduleForComponent('Component Integration Tests', {
     setResolverRegistry({
       'template:components/my-component': Ember.Handlebars.compile(
         '<span>{{name}}</span>'
-      )
+      ),
+      'component:bad-component': BadComponent
     });
   }
 });
@@ -395,6 +412,13 @@ if (hasEmberVersion(1,11)) {
   });
 }
 
+test('it correctly handles uncaught errors when rendering a component', function() {
+  var self = this;
+  throws(function() {
+    self.render('{{bad-component}}');
+  });
+});
+
 test('it complains if you try to use bare render', function() {
   var self = this;
   throws(function() {