feat(resolve): Remove RXWAIT async policy in favour of allowing user defined async policy function (#366)

BREAKING CHANGE: RXWAIT async policy has been removed, but it never worked in the first place

Author: wawyed

src/resolve/interface.ts

@@ -200,7 +200,8 @@ export interface ResolvePolicy {
 }
 
 export type PolicyWhen = 'LAZY' | 'EAGER';
-export type PolicyAsync = 'WAIT' | 'NOWAIT' | 'RXWAIT';
+export type PolicyAsync = 'WAIT' | 'NOWAIT' | CustomAsyncPolicy;
+export type CustomAsyncPolicy = <TResolveFnResult, TResolveValue>(data: TResolveFnResult) => Promise<TResolveValue>;
 
 /** @internalapi */
 export let resolvePolicies = {

src/resolve/resolvable.ts

@@ -1,8 +1,8 @@
 /** @publicapi @module resolve */ /** */
-import { extend, equals, inArray, identity } from '../common/common';
+import { extend, identity } from '../common/common';
 import { services } from '../common/coreservices';
 import { trace } from '../common/trace';
-import { ResolvePolicy, ResolvableLiteral, resolvePolicies } from './interface';
+import { ResolvePolicy, ResolvableLiteral, PolicyAsync } from './interface';
 
 import { ResolveContext } from './resolveContext';
 import { stringify } from '../common/strings';
@@ -117,26 +117,12 @@ export class Resolvable implements ResolvableLiteral {
     // Invokes the resolve function passing the resolved dependencies as arguments
     const invokeResolveFn = (resolvedDeps: any[]) => this.resolveFn.apply(null, resolvedDeps);
 
-    /**
-     * For RXWAIT policy:
-     *
-     * Given an observable returned from a resolve function:
-     * - enables .cache() mode (this allows multicast subscribers)
-     * - then calls toPromise() (this triggers subscribe() and thus fetches)
-     * - Waits for the promise, then return the cached observable (not the first emitted value).
-     */
-    const waitForRx = (observable$: any) => {
-      const cached = observable$.cache(1);
-      return cached
-        .take(1)
-        .toPromise()
-        .then(() => cached);
-    };
-
     // If the resolve policy is RXWAIT, wait for the observable to emit something. otherwise pass through.
     const node: PathNode = resolveContext.findNode(this);
     const state: StateObject = node && node.state;
-    const maybeWaitForRx = this.getPolicy(state).async === 'RXWAIT' ? waitForRx : identity;
+
+    const asyncPolicy: PolicyAsync = this.getPolicy(state).async;
+    const customAsyncPolicy = isFunction(asyncPolicy) ? asyncPolicy : identity;
 
     // After the final value has been resolved, update the state of the Resolvable
     const applyResolvedValue = (resolvedValue: any) => {
@@ -152,7 +138,7 @@ export class Resolvable implements ResolvableLiteral {
       .when()
       .then(getResolvableDependencies)
       .then(invokeResolveFn)
-      .then(maybeWaitForRx)
+      .then(customAsyncPolicy)
       .then(applyResolvedValue));
   }
 

test/resolveSpec.ts

@@ -1,13 +1,13 @@
-import { ResolveContext, StateObject, PathNode, Resolvable, copy } from '../src/index';
+import { tail } from '../src/common/common';
 import { services } from '../src/common/coreservices';
-import { tree2Array } from './_testUtils';
+import { copy, CustomAsyncPolicy, PathNode, Resolvable, ResolveContext, StateObject } from '../src/index';
 import { UIRouter } from '../src/router';
-
-import { TestingPlugin } from './_testingPlugin';
+import { StateRegistry } from '../src/state/stateRegistry';
 import { StateService } from '../src/state/stateService';
 import { TransitionService } from '../src/transition/transitionService';
-import { StateRegistry } from '../src/state/stateRegistry';
-import { tail } from '../src/common/common';
+
+import { TestingPlugin } from './_testingPlugin';
+import { tree2Array } from './_testUtils';
 
 ///////////////////////////////////////////////
 
@@ -426,6 +426,7 @@ describe('Resolvables system:', function() {
       const ctx = new ResolveContext(path);
 
       let result;
+
       function checkCounts() {
         expect(result).toBe('JJ2K');
         expect(counts['_J']).toBe(1);
@@ -561,10 +562,11 @@ describe('Resolvables system:', function() {
 
   describe('NOWAIT Resolve Policy', () => {
     it('should allow a transition to complete before the resolve is settled', async done => {
-      let resolve,
-        resolvePromise = new Promise(_resolve => {
-          resolve = _resolve;
-        });
+      let resolve;
+
+      const resolvePromise = new Promise(_resolve => {
+        resolve = _resolve;
+      });
 
       $registry.register({
         name: 'nowait',
@@ -599,10 +601,11 @@ describe('Resolvables system:', function() {
     });
 
     it('should wait for WAIT resolves and not wait for NOWAIT resolves', async done => {
-      let promiseResolveFn,
-        resolvePromise = new Promise(resolve => {
-          promiseResolveFn = resolve;
-        });
+      let promiseResolveFn;
+
+      const resolvePromise = new Promise(resolve => {
+        promiseResolveFn = resolve;
+      });
 
       $registry.register({
         name: 'nowait',
@@ -635,4 +638,39 @@ describe('Resolvables system:', function() {
       $state.go('nowait');
     });
   });
+
+  describe('custom Resolve Policy', () => {
+    let customResolvePolicy: CustomAsyncPolicy;
+
+    it('should wait for the promise to resolve before finishing the transition', async done => {
+      let resolve: (value: string) => void;
+
+      const resolvePromise: Promise<string> = new Promise(_resolve => {
+        resolve = _resolve;
+      });
+
+      customResolvePolicy = jasmine.createSpy('customResolvePolicy');
+
+      (customResolvePolicy as jasmine.Spy).and.callFake((data: { useMe: Promise<string> }) => {
+        return data.useMe;
+      });
+
+      resolve('myAwaitedValue');
+
+      $registry.register({
+        name: 'customPolicy',
+        resolve: {
+          customWait: () => ({ useMe: resolvePromise }),
+        },
+        resolvePolicy: { async: customResolvePolicy },
+      });
+
+      $transitions.onSuccess({}, trans => {
+        expect(customResolvePolicy).toHaveBeenCalledWith({ useMe: resolvePromise });
+        expect(trans.injector().get('customWait')).toBe('myAwaitedValue');
+      });
+
+      $state.go('customPolicy').then(done);
+    });
+  });
 });