fix(Transition): Use { location: replace } when redirecting a transtition in response to a URL sync

This fixes a problem that occurred when the url sync caused a redirection:

- URL changes (to `/foo`)
- Router synchronizes
- Router redirects elsewhere (to `/bar`)
- Url is updated

Now the browser history has two history entries:

- `/foo`
- `/bar`

---

Now, when the URL is updated, it uses `{ location: replace }` so the browser history only has one entry:

- `/bar`

Closes angular-ui/ui-router#3187
Closes #15

Author: christopherthielen

src/transition/transition.ts

@@ -508,7 +508,15 @@ export class Transition implements IHookRegistry {
       if (++redirects > 20) throw new Error(`Too many consecutive Transition redirects (20+)`);
     }
 
-    let newOptions = extend({}, this.options(), targetState.options(), { redirectedFrom: this, source: "redirect" });
+    let redirectOpts: TransitionOptions = { redirectedFrom: this, source: "redirect" };
+    // If the original transition was caused by URL sync, then use { location: 'replace' }
+    // on the new transition (unless  the target state explicitly specifies location)
+    if (this.options().source === 'url') {
+      redirectOpts.location = 'replace';
+    }
+
+    let newOptions = extend({}, this.options(), targetState.options(), redirectOpts);
+
     targetState = new TargetState(targetState.identifier(), targetState.$state(), targetState.params(), newOptions);
 
     let newTransition = this.router.transitionService.create(this._treeChanges.from, targetState);

test/transitionSpec.ts

@@ -2,8 +2,8 @@ import { PathNode } from "../src/path/node";
 import {
     UIRouter, RejectType, Rejection, pluck, services, TransitionService, StateService, Resolvable, Transition
 } from "../src/index";
-import * as vanilla from "../src/vanilla";
 import { tree2Array, PromiseResult } from "./_testUtils";
+import { TestingPlugin } from "./_testingPlugin";
 
 describe('transition', function () {
 
@@ -30,8 +30,7 @@ describe('transition', function () {
 
   beforeEach(() => {
     router = new UIRouter();
-    router.plugin(vanilla.servicesPlugin);
-    router.plugin(vanilla.hashLocationPlugin);
+    router.plugin(TestingPlugin);
     $state = router.stateService;
     $transitions = router.transitionService;
 
@@ -60,7 +59,7 @@ describe('transition', function () {
     states.forEach(state => router.stateRegistry.register(state));
   });
 
-  describe('provider', () => {
+  describe('service', () => {
     describe('async event hooks:', () => {
       it('$transition$.promise should resolve on success', (done) => {
         var result = new PromiseResult();
@@ -674,6 +673,41 @@ describe('transition', function () {
             .then(done, done);
       }));
     });
+
+    describe('redirected transition', () => {
+      let urlRedirect;
+      beforeEach(() => {
+        urlRedirect = router.stateRegistry.register({ name: 'urlRedirect', url: '/urlRedirect', redirectTo: 'redirectTarget' });
+        router.stateRegistry.register({ name: 'redirectTarget', url: '/redirectTarget' });
+      });
+
+      it("should not replace the current url when redirecting a state.go transition", async (done) => {
+        let spy = spyOn(router.urlService, "url").and.callThrough();
+
+        await $state.go("urlRedirect");
+        expect(router.urlService.path()).toBe("/redirectTarget");
+        expect(spy).toHaveBeenCalledWith("/redirectTarget", false);
+        done();
+      });
+
+      it("should replace the current url when redirecting a url sync", (done) => {
+        let url = spyOn(router.urlService, "url").and.callThrough();
+        let transitionTo = spyOn(router.stateService, "transitionTo").and.callThrough();
+
+        router.transitionService.onSuccess({}, () => {
+          expect(transitionTo).toHaveBeenCalledWith(urlRedirect, {}, { inherit: true, source: 'url' });
+
+          expect(url.calls.count()).toEqual(2);
+          expect(url.calls.argsFor(0)).toEqual(["/urlRedirect"]);
+          expect(url.calls.argsFor(1)).toEqual(["/redirectTarget", true]);
+
+          done();
+        });
+
+        router.urlService.url('/urlRedirect');
+      });
+
+    });
   });
 
   describe('Transition() instance', function() {
@@ -749,4 +783,8 @@ describe('transition', function () {
       }));
     });
   });
+});
+
+describe("initial url redirect", () => {
+
 });