Failing test case for lazily loaded engines with loading states

packages/@ember/-internals/routing/lib/utils.ts

@@ -66,9 +66,11 @@ export function stashParamNames(router: EmberRouter, routeInfos: PrivateRouteInf
 
     routeInfo['_names'] = names;
 
-    let route = routeInfo.route!;
+    let route = routeInfo.route;
+    if (route !== undefined) {
       route._stashNames(routeInfo, dynamicParent!);
     }
+  }
 
   routeInfos['_namesStashed'] = true;
 }

packages/ember/tests/routing/model_loading_test.js

@@ -5,12 +5,12 @@ import { Object as EmberObject, A as emberA } from '@ember/-internals/runtime';
 import { moduleFor, ApplicationTestCase, getTextOf } from 'internal-test-helpers';
 import { run } from '@ember/runloop';
 import { computed, set } from '@ember/-internals/metal';
+import { isDestroying } from '@glimmer/destroyable';
+import RSVP from 'rsvp';
 
 let originalConsoleError;
 
-moduleFor(
-  'Route - model loading',
-  class extends ApplicationTestCase {
+class LoadingTests extends ApplicationTestCase {
   constructor() {
     super(...arguments);
     this.addTemplate('home', '<h3 class="hours">Hours</h3>');
@@ -137,11 +137,7 @@ moduleFor(
     return this.visit('/').then(() => {
       let text = this.$('ul li:nth-child(3)').text();
 
-        assert.equal(
-          text,
-          'Sunday: Noon to 6pm',
-          'The template was rendered with the hours context'
-        );
+      assert.equal(text, 'Sunday: Noon to 6pm', 'The template was rendered with the hours context');
     });
   }
 
@@ -162,11 +158,7 @@ moduleFor(
       let homeRoute = this.applicationInstance.lookup('route:home');
       let homeController = this.applicationInstance.lookup('controller:home');
 
-        assert.equal(
-          homeRoute.controller,
-          homeController,
-          'route controller is the home controller'
-        );
+      assert.equal(homeRoute.controller, homeController, 'route controller is the home controller');
     });
   }
 
@@ -190,11 +182,7 @@ moduleFor(
       let myController = this.applicationInstance.lookup('controller:myController');
       let text = this.$('p').text();
 
-        assert.equal(
-          homeRoute.controller,
-          myController,
-          'route controller is set by controllerName'
-        );
+      assert.equal(homeRoute.controller, myController, 'route controller is set by controllerName');
       assert.equal(
         text,
         'foo',
@@ -236,11 +224,7 @@ moduleFor(
       let myController = this.applicationInstance.lookup('controller:myController');
       let text = this.$('p').text();
 
-        assert.equal(
-          homeRoute.controller,
-          myController,
-          'route controller is set by controllerName'
-        );
+      assert.equal(homeRoute.controller, myController, 'route controller is set by controllerName');
 
       assert.equal(
         text,
@@ -285,11 +269,7 @@ moduleFor(
       let myController = this.applicationInstance.lookup('controller:myController');
       let text = this.$('p').text();
 
-        assert.equal(
-          homeRoute.controller,
-          myController,
-          'route controller is set by controllerName'
-        );
+      assert.equal(homeRoute.controller, myController, 'route controller is set by controllerName');
 
       assert.equal(
         text,
@@ -317,19 +297,12 @@ moduleFor(
       })
     );
 
-      this.addTemplate(
-        'home',
-        '<ul>{{#each this.hours as |entry|}}<li>{{entry}}</li>{{/each}}</ul>'
-      );
+    this.addTemplate('home', '<ul>{{#each this.hours as |entry|}}<li>{{entry}}</li>{{/each}}</ul>');
 
     return this.visit('/').then(() => {
       let text = this.$('ul li:nth-child(3)').text();
 
-        assert.equal(
-          text,
-          'Sunday: Noon to 6pm',
-          'The template was rendered with the hours context'
-        );
+      assert.equal(text, 'Sunday: Noon to 6pm', 'The template was rendered with the hours context');
     });
   }
 
@@ -391,19 +364,12 @@ moduleFor(
       })
     );
 
-      this.addTemplate(
-        'home',
-        '<ul>{{#each this.hours as |entry|}}<li>{{entry}}</li>{{/each}}</ul>'
-      );
+    this.addTemplate('home', '<ul>{{#each this.hours as |entry|}}<li>{{entry}}</li>{{/each}}</ul>');
 
     return this.visit('/').then(() => {
       let text = this.$('ul li:nth-child(3)').text();
 
-        assert.equal(
-          text,
-          'Sunday: Noon to 6pm',
-          'The template was rendered with the hours context'
-        );
+      assert.equal(text, 'Sunday: Noon to 6pm', 'The template was rendered with the hours context');
     });
   }
 
@@ -863,11 +829,7 @@ moduleFor(
       run(() => router.send('showPost', { id: '2' }));
       run(() => router.send('editPost'));
       assert.equal(editCount, 2, 'set up the edit route twice without failure');
-        assert.deepEqual(
-          editedPostIds,
-          ['1', '2'],
-          'modelFor posts.post returns the right context'
-        );
+      assert.deepEqual(editedPostIds, ['1', '2'], 'modelFor posts.post returns the right context');
     });
   }
 
@@ -891,11 +853,7 @@ moduleFor(
     return this.visit('/').then(() => {
       let routerService = this.applicationInstance.lookup('service:router');
       assert.equal(routerService.currentRouteName, 'index', 'currentPath is index');
-        assert.equal(
-          'currentPath' in model,
-          false,
-          'should have defined currentPath on controller'
-        );
+      assert.equal('currentPath' in model, false, 'should have defined currentPath on controller');
     });
   }
 
@@ -984,4 +942,50 @@ moduleFor(
       });
   }
 }
+
+moduleFor('Route - model loading', LoadingTests);
+
+moduleFor(
+  'Route - model loading (simulated within lazy engine)',
+  class extends LoadingTests {
+    get routerOptions() {
+      return {
+        location: 'none',
+        setupRouter() {
+          this._super(...arguments);
+          let getRoute = this._routerMicrolib.getRoute;
+          this._enginePromises = Object.create(null);
+          this._resolvedEngines = Object.create(null);
+
+          let routes = new Map();
+          let routePromises = new Map();
+          this._routerMicrolib.getRoute = (name) => {
+            if (routes.has(name)) {
+              return routes.get(name);
+            }
+
+            if (routePromises.has(name)) {
+              return routePromises.get(name);
+            }
+
+            let promise = new RSVP.Promise((resolve) => {
+              setTimeout(() => {
+                if (isDestroying(this)) {
+                  return;
+                }
+
+                let route = getRoute(name);
+
+                routes.set(name, route);
+                resolve(route);
+              }, 10);
+            });
+            routePromises.set(name, promise);
+
+            return promise;
+          };
+        },
+      };
+    }
+  }
 );