feat(abort): Add API to manually abort/cancel a transition

src/transition/transition.ts

@@ -8,7 +8,7 @@ import { services } from '../common/coreservices';
 import {
   map, find, extend, mergeR, tail, omit, toJson, arrayTuples, unnestR, identity, anyTrueR,
 } from '../common/common';
-import { isObject } from '../common/predicates';
+import {isObject, isUndefined} from '../common/predicates';
 import { prop, propEq, val, not, is } from '../common/hof';
 import { StateDeclaration, StateOrName } from '../state/interface';
 import {
@@ -74,10 +74,14 @@ export class Transition implements IHookRegistry {
    * A boolean which indicates if the transition was successful
    *
    * After a successful transition, this value is set to true.
-   * After a failed transition, this value is set to false.
+   * After an unsuccessful transition, this value is set to false.
+   *
+   * The value will be undefined if the transition is not complete
    */
   success: boolean;
   /** @hidden */
+  _aborted: boolean;
+  /** @hidden */
   private _error: any;
 
   /** @hidden Holds the hook registration functions such as those passed to Transition.onStart() */
@@ -681,6 +685,19 @@ export class Transition implements IHookRegistry {
     return !this.error() || this.success !== undefined;
   }
 
+  /**
+   * Aborts this transition
+   *
+   * Imperative API to abort a Transition.
+   * This only applies to Transitions that are not yet complete.
+   */
+  abort() {
+    // Do not set flag if the transition is already complete
+    if (isUndefined(this.success))  {
+      this._aborted = true;
+    }
+  }
+
   /**
    * The Transition error reason.
    *

src/transition/transitionHook.ts

@@ -21,7 +21,7 @@ let defaultOptions: TransitionHookOptions = {
   current: noop,
   transition: null,
   traceData: {},
-  bind: null
+  bind: null,
 };
 
 export type GetResultHandler = (hook: TransitionHook) => ResultHandler;
@@ -56,7 +56,7 @@ export class TransitionHook {
     isPromise(result) && result.catch(err =>
         hook.logError(Rejection.normalize(err)));
     return undefined;
-  };
+  }
 
   /**
    * These GetErrorHandler(s) are used by [[invokeHook]] below
@@ -70,7 +70,7 @@ export class TransitionHook {
 
   static THROW_ERROR: GetErrorHandler = (hook: TransitionHook) => (error: any) => {
     throw error;
-  };
+  }
 
   private isSuperseded = () =>
     this.type.hookPhase === TransitionHookPhase.RUN && !this.options.transition.isActive();
@@ -164,6 +164,10 @@ export class TransitionHook {
       return Rejection.aborted(`UIRouter instance #${router.$id} has been stopped (disposed)`).toPromise();
     }
 
+    if (this.transition._aborted) {
+      return Rejection.aborted().toPromise();
+    }
+
     // This transition is no longer current.
     // Another transition started while this hook was still running.
     if (this.isSuperseded()) {

test/stateServiceSpec.ts

@@ -497,7 +497,7 @@ describe('stateService', function () {
       done();
     });
 
-    it('is a no-op when passing the current state and identical parameters', async(done) => {
+    it('is ignored when passing the current state and identical parameters', async(done) => {
       let enterlog = "";
       $transitions.onEnter({ entering: 'A'}, (trans, state) => { enterlog += state.name + ";" });
       await initStateTo(A);
@@ -542,6 +542,30 @@ describe('stateService', function () {
       done();
     });
 
+    it('can be manually aborted', async(done) => {
+      $state.defaultErrorHandler(() => null);
+
+      await initStateTo(A);
+
+      router.transitionService.onStart({}, trans => {
+        if (trans.$id === 1) return new Promise(resolve => setTimeout(resolve, 50)) as any;
+      });
+
+      let promise = $state.transitionTo(B, {});
+      let transition = promise.transition;
+
+      setTimeout(() => transition.abort());
+
+      const expects = (result) => {
+        expect($state.current).toBe(A);
+        expect(result.type).toBe(RejectType.ABORTED);
+
+        done();
+      };
+
+      promise.then(expects, expects);
+    });
+
     it('aborts pending transitions when superseded from callbacks', async(done) => {
       // router.trace.enable(1);
       $state.defaultErrorHandler(() => null);