feat(router): add reuse support for angular 1.x router

Closes #3698

modules/angular1_router/test/ng_outlet_spec.js

@@ -358,6 +358,76 @@ describe('ngOutlet', function () {
   });
 
 
+  it('should reuse a component when the canReuse hook returns true', function () {
+    var log = [];
+    var cmpInstanceCount = 0;
+
+    function ReuseCmp() {
+      cmpInstanceCount++;
+      this.canReuse = function () {
+        return true;
+      };
+      this.onReuse = function (next, prev) {
+        log.push('reuse: ' + prev.urlPath + ' -> ' + next.urlPath);
+      };
+    }
+    ReuseCmp.$routeConfig = [{path: '/a', component: OneController}, {path: '/b', component: TwoController}];
+    registerComponent('reuse', 'reuse {<ng-outlet></ng-outlet>}', ReuseCmp);
+
+    $router.config([
+      { path: '/on-reuse/:number/...', component: ReuseCmp }
+    ]);
+    compile('outer { <div ng-outlet></div> }');
+
+    $router.navigate('/on-reuse/1/a');
+    $rootScope.$digest();
+    expect(log).toEqual([]);
+    expect(cmpInstanceCount).toBe(1);
+    expect(elt.text()).toBe('outer { reuse {one} }');
+
+    $router.navigate('/on-reuse/2/b');
+    $rootScope.$digest();
+    expect(log).toEqual(['reuse: on-reuse/1 -> on-reuse/2']);
+    expect(cmpInstanceCount).toBe(1);
+    expect(elt.text()).toBe('outer { reuse {two} }');
+  });
+
+
+  it('should not reuse a component when the canReuse hook returns false', function () {
+    var log = [];
+    var cmpInstanceCount = 0;
+
+    function NeverReuseCmp() {
+      cmpInstanceCount++;
+      this.canReuse = function () {
+        return false;
+      };
+      this.onReuse = function (next, prev) {
+        log.push('reuse: ' + prev.urlPath + ' -> ' + next.urlPath);
+      };
+    }
+    NeverReuseCmp.$routeConfig = [{path: '/a', component: OneController}, {path: '/b', component: TwoController}];
+    registerComponent('reuse', 'reuse {<ng-outlet></ng-outlet>}', NeverReuseCmp);
+
+    $router.config([
+      { path: '/never-reuse/:number/...', component: NeverReuseCmp }
+    ]);
+    compile('outer { <div ng-outlet></div> }');
+
+    $router.navigate('/never-reuse/1/a');
+    $rootScope.$digest();
+    expect(log).toEqual([]);
+    expect(cmpInstanceCount).toBe(1);
+    expect(elt.text()).toBe('outer { reuse {one} }');
+
+    $router.navigate('/never-reuse/2/b');
+    $rootScope.$digest();
+    expect(log).toEqual([]);
+    expect(cmpInstanceCount).toBe(2);
+    expect(elt.text()).toBe('outer { reuse {two} }');
+  });
+
+
   it('should not activate a component when canActivate returns false', function () {
     var spy = jasmine.createSpy('activate');
     var activate = registerComponent('activate', '', {