[BUGFIX] {{link-to}} before application boot

packages/ember-routing-views/lib/views/link.js

@@ -259,6 +259,8 @@ var LinkComponent = EmberComponent.extend({
   */
   active: computed('attrs.params', '_routing.currentState', function computeLinkComponentActive() {
     var currentState = get(this, '_routing.currentState');
+    if (!currentState) { return false; }
+
     return computeActive(this, currentState);
   }),
 

packages/ember-routing/lib/services/routing.js

@@ -53,6 +53,7 @@ var RoutingService = Service.extend({
 
   generateURL(routeName, models, queryParams) {
     var router = get(this, 'router');
+    if (!router.router) { return; }
 
     var visibleQueryParams = {};
     merge(visibleQueryParams, queryParams);

packages/ember/tests/helpers/link_to_test.js

@@ -1,4 +1,5 @@
 import "ember";
+import ComponentLookup from "ember-views/component_lookup";
 
 import { objectControllerDeprecation } from "ember-runtime/controllers/object_controller";
 import EmberHandlebars from "ember-htmlbars/compat";
@@ -93,6 +94,45 @@ QUnit.module("The {{link-to}} helper", {
   teardown: sharedTeardown
 });
 
+// These two tests are designed to simulate the context of an ember-qunit/ember-test-helpers component integration test,
+// so the container is available but it does not boot the entire app
+QUnit.test('Using {{link-to}} does not cause an exception if it is rendered before the router has started routing', function(assert) {
+  Router.map(function() {
+    this.route('about');
+  });
+
+  registry.register('component-lookup:main', ComponentLookup);
+
+  let component = Ember.Component.extend({
+    layout: compile('{{#link-to "about"}}Go to About{{/link-to}}'),
+    container: container
+  }).create();
+
+  let router = container.lookup('router:main');
+  router.setupRouter();
+
+  Ember.run(function() {
+    component.appendTo('#qunit-fixture');
+  });
+
+  assert.strictEqual(component.$('a').length, 1, 'the link is rendered');
+});
+
+QUnit.test('Using {{link-to}} does not cause an exception if it is rendered without a router.js instance', function(assert) {
+  registry.register('component-lookup:main', ComponentLookup);
+
+  let component = Ember.Component.extend({
+    layout: compile('{{#link-to "nonexistent"}}Does not work.{{/link-to}}'),
+    container: container
+  }).create();
+
+  Ember.run(function() {
+    component.appendTo('#qunit-fixture');
+  });
+
+  assert.strictEqual(component.$('a').length, 1, 'the link is rendered');
+});
+
 QUnit.test("The {{link-to}} helper moves into the named route", function() {
   Router.map(function(match) {
     this.route("about");