BC-BREAK: Change Transition.previous() to Transition.redirectedFrom()

refactor(Transition): BC-BREAK: Change Transition.previous() to Transition.redirectedFrom()
- redirectedFrom is more accurate

fix(redirect): Allow URL-sync() redirect targets to update the URL
- A URL sync uses { location: false }.  When a transition redirects a URL sync, the options are retained.
- Now URL sync uses { source: 'url' } and redirects override that with { source: 'redirect' }.
   When synchronizing URL, either { source: 'url' } or { location: false } skips url update.

Closes #2966

src/hooks/url.ts

@@ -15,7 +15,11 @@ const updateUrl: TransitionHookFn = (transition: Transition) => {
   let $state: StateService = transition.router.stateService;
   let $urlRouter: UrlRouter = transition.router.urlRouter;
 
-  if (options.location && $state.$current.navigable) {
+  // Dont update the url in these situations:
+  // The transition was triggered by a URL sync (options.source === 'url')
+  // The user doesn't want the url to update (options.location === false)
+  // The destination state, and all parents have no navigable url
+  if (options.source !== 'url' && options.location && $state.$current.navigable) {
     var urlOptions = {replace: options.location === 'replace'};
     $urlRouter.push($state.$current.navigable.url, $state.params, urlOptions);
   }

src/state/stateQueueManager.ts

@@ -96,7 +96,7 @@ export class StateQueueManager {
 
     $urlRouterProvider.when(state.url, ['$match', '$stateParams', function ($match: RawParams, $stateParams: RawParams) {
       if ($state.$current.navigable !== state || !equalForKeys($match, $stateParams)) {
-        $state.transitionTo(state, $match, { inherit: true, location: false, source: "url" });
+        $state.transitionTo(state, $match, { inherit: true, source: "url" });
       }
     }], (rule) => state._urlRule = rule);
   }

src/transition/interface.ts

@@ -75,12 +75,14 @@ export interface TransitionOptions {
   custom      ?: any;
   /** @hidden @internal */
   reloadState ?: (State);
-  /** @hidden @internal */
-  previous    ?: Transition;
+  /** @hidden @internal
+   * If this transition is a redirect, this property should be the original Transition (which was redirected to this one)
+   */
+  redirectedFrom?: Transition;
   /** @hidden @internal */
   current     ?: () => Transition;
   /** @hidden @internal */
-  source      ?: "sref"|"url"|"unknown";
+  source      ?: "sref"|"url"|"redirect"|"unknown";
 }
 
 /** @hidden @internal */

src/transition/transition.ts

@@ -297,12 +297,26 @@ export class Transition implements IHookRegistry {
   }
 
   /**
-   * Gets the previous transition, from which this transition was redirected.
+   * If the current transition is a redirect, returns the transition that was redirected.
+   *
+   * Gets the transition from which this transition was redirected.
+   *
+   *
+   * @example
+   * ```js
+   *
+   * let transitionA = $state.go('A').transitionA
+   * transitionA.onStart({}, () => $state.target('B'));
+   * $transitions.onSuccess({ to: 'B' }, (trans) => {
+   *   trans.to().name === 'B'; // true
+   *   trans.redirectedFrom() === transitionA; // true
+   * });
+   * ```
    *
    * @returns The previous Transition, or null if this Transition is not the result of a redirection
    */
-  previous(): Transition {
-    return this._options.previous || null;
+  redirectedFrom(): Transition {
+    return this._options.redirectedFrom || null;
   }
 
   /**
@@ -371,7 +385,7 @@ export class Transition implements IHookRegistry {
    * @returns Returns a new [[Transition]] instance.
    */
   redirect(targetState: TargetState): Transition {
-    let newOptions = extend({}, this.options(), targetState.options(), { previous: this });
+    let newOptions = extend({}, this.options(), targetState.options(), { redirectedFrom: this, source: "redirect" });
     targetState = new TargetState(targetState.identifier(), targetState.$state(), targetState.params(), newOptions);
 
     let newTransition = this.router.transitionService.create(this._treeChanges.from, targetState);

test/core/stateServiceSpec.ts

@@ -0,0 +1,95 @@
+import { UIRouter
+    TransitionService,
+    StateService,
+} from "../../src/core";
+import "../../src/justjs";
+import {tree2Array} from "../testUtils.ts";
+import {TransitionOptions} from "../../src/transition/interface";
+import {LocationServices, services} from "../../src/common/coreservices";
+
+describe('stateService', function () {
+  let router: UIRouter;
+  let $transitions: TransitionService;
+  let $state: StateService;
+  let $loc: LocationServices;
+
+  const wait = (val?) =>
+      new Promise((resolve) => setTimeout(() => resolve(val)));
+
+  beforeEach(() => {
+    router = new UIRouter();
+    $loc = services.location;
+    $state = router.stateService;
+    $transitions = router.transitionService;
+    router.stateRegistry.stateQueue.autoFlush($state);
+
+    var stateTree = {
+      first: {},
+      second: {},
+      third: {},
+      A: {
+        url: '/a',
+        B: {
+          url: '/b',
+          C: {
+            url: '/c',
+            D: {
+              url: '/d'
+            }
+          }
+        }
+      }
+    };
+
+    let states = tree2Array(stateTree, false);
+    states.forEach(state => router.stateRegistry.register(state));
+  });
+
+  describe('transitionTo', () => {
+
+    it("should handle redirects", ((done) => {
+      $transitions.onStart({ to: 'D'}, trans => (log.push('redirect'), trans.router.stateService.target('C')));
+      $transitions.onStart({ to: 'C'}, trans => { cOpts = trans.options(); });
+
+      var log = [], transition = $state.go("D").transition;
+      var cOpts: TransitionOptions = {};
+
+      wait().then(() => {
+        expect(log).toEqual(['redirect']);
+        expect(cOpts.redirectedFrom).toBe(transition);
+        expect(cOpts.source).toBe("redirect");
+      })
+      .then(done, done);
+    }));
+
+    it("should not update the URL in response to synchronizing URL", ((done) => {
+      $loc.url('/a/b/c');
+      spyOn($loc, 'url').and.callThrough();
+      router.urlRouter.sync();
+
+      wait().then(() => {
+        expect($state.current.name).toBe('C');
+        let pushedUrls = $loc.url.calls.all().map(x => x.args[0]).filter(x => x !== undefined);
+        expect(pushedUrls).toEqual([]);
+        expect($loc.path()).toBe('/a/b/c');
+        done();
+      })
+    }));
+
+    it("should update the URL in response to synchronizing URL then redirecting", ((done) => {
+      $transitions.onStart({ to: 'C' }, () => $state.target('D'));
+
+      $loc.url('/a/b/c');
+      spyOn($loc, 'url').and.callThrough();
+      router.urlRouter.sync();
+
+      wait().then(() => {
+        expect($state.current.name).toBe('D');
+        let pushedUrls = $loc.url.calls.all().map(x => x.args[0]).filter(x => x !== undefined);
+        expect(pushedUrls).toEqual(['/a/b/c/d']);
+        expect($loc.path()).toBe('/a/b/c/d');
+        done();
+      })
+    }));
+  });
+});