feat(promise): support Promise.prototype.finally (#1005)

.travis.yml

@@ -29,6 +29,7 @@ script:
   - node_modules/.bin/gulp filesize
   - scripts/closure/closure_compiler.sh
   - node_modules/.bin/gulp promisetest
+  - npm run promisefinallytest
   - npm run test:phantomjs-single
   - node_modules/.bin/karma start karma-dist-sauce-jasmine.conf.js --single-run
   - node_modules/.bin/karma start karma-build-sauce-mocha.conf.js --single-run

gulpfile.js

@@ -427,6 +427,8 @@ gulp.task('promisetest', ['build/zone-node.js'], (cb) => {
     promisesAplusTests(adapter, { reporter: "dot" }, function (err) {
       if (err) {
         cb(err);
+      } else {
+        cb();
       }
     });
 });

lib/common/promise.ts

@@ -5,6 +5,10 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+interface Promise<T> {
+  finally<U>(onFinally?: () => U | PromiseLike<U>): Promise<T>;
+}
+
 Zone.__load_patch('ZoneAwarePromise', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
   const ObjectGetOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
   const ObjectDefineProperty = Object.defineProperty;
@@ -88,6 +92,9 @@ Zone.__load_patch('ZoneAwarePromise', (global: any, Zone: ZoneType, api: _ZonePr
 
   const symbolState: string = __symbol__('state');
   const symbolValue: string = __symbol__('value');
+  const symbolFinally: string = __symbol__('finally');
+  const symbolParentPromiseValue: string = __symbol__('parentPromiseValue');
+  const symbolParentPromiseState: string = __symbol__('parentPromiseState');
   const source: string = 'Promise.then';
   const UNRESOLVED: null = null;
   const RESOLVED = true;
@@ -163,6 +170,16 @@ Zone.__load_patch('ZoneAwarePromise', (global: any, Zone: ZoneType, api: _ZonePr
         const queue = (promise as any)[symbolValue];
         (promise as any)[symbolValue] = value;
 
+        if ((promise as any)[symbolFinally] === symbolFinally) {
+          // the promise is generated by Promise.prototype.finally          
+          if (state === RESOLVED) {
+            // the state is resolved, should ignore the value
+            // and use parent promise value
+            (promise as any)[symbolState] = (promise as any)[symbolParentPromiseState];
+            (promise as any)[symbolValue] = (promise as any)[symbolParentPromiseValue];
+          }
+        }
+
         // record task information in value when error occurs, so we can
         // do some additional work such as render longStackTrace
         if (state === REJECTED && value instanceof Error) {
@@ -231,14 +248,24 @@ Zone.__load_patch('ZoneAwarePromise', (global: any, Zone: ZoneType, api: _ZonePr
       promise: ZoneAwarePromise<any>, zone: AmbientZone, chainPromise: ZoneAwarePromise<any>,
       onFulfilled?: (value: R) => U1, onRejected?: (error: any) => U2): void {
     clearRejectedNoCatch(promise);
-    const delegate = (promise as any)[symbolState] ?
+    const promiseState = (promise as any)[symbolState];
+    const delegate = promiseState ?
         (typeof onFulfilled === 'function') ? onFulfilled : forwardResolution :
         (typeof onRejected === 'function') ? onRejected : forwardRejection;
     zone.scheduleMicroTask(source, () => {
       try {
-        resolvePromise(
-            chainPromise, true, zone.run(delegate, undefined, [(promise as any)[symbolValue]]));
+        const parentPromiseValue = (promise as any)[symbolValue];
+        const isFinallyPromise = chainPromise && symbolFinally === (chainPromise as any)[symbolFinally];
+        if (isFinallyPromise) {
+          // if the promise is generated from finally call, keep parent promise's state and value
+          (chainPromise as any)[symbolParentPromiseValue] = parentPromiseValue;
+          (chainPromise as any)[symbolParentPromiseState] = promiseState;
+        }
+        // should not pass value to finally callback
+        const value = zone.run(delegate, undefined, isFinallyPromise && delegate !== forwardRejection && delegate !== forwardResolution ? [] : [parentPromiseValue]);
+        resolvePromise(chainPromise, true, value);
       } catch (error) {
+        // if error occurs, should always return this error
         resolvePromise(chainPromise, false, error);
       }
     });
@@ -345,6 +372,19 @@ Zone.__load_patch('ZoneAwarePromise', (global: any, Zone: ZoneType, api: _ZonePr
                            null): Promise<R|TResult> {
       return this.then(null, onRejected);
     }
+
+    finally<U>(onFinally?: () => U | PromiseLike<U>): Promise<R> {
+      const chainPromise: Promise<R|never> =
+          new (this.constructor as typeof ZoneAwarePromise)(null);
+      (chainPromise as any)[symbolFinally] = symbolFinally;
+      const zone = Zone.current;
+      if ((this as any)[symbolState] == UNRESOLVED) {
+        (<any[]>(this as any)[symbolValue]).push(zone, chainPromise, onFinally, onFinally);
+      } else {
+        scheduleResolveOrReject(this, zone, chainPromise, onFinally, onFinally);
+      }
+      return chainPromise;
+    }
   }
   // Protect against aggressive optimizers dropping seemingly unused properties.
   // E.g. Closure Compiler in advanced mode.

package.json

@@ -27,6 +27,7 @@
     "lint": "gulp lint",
     "prepublish": "tsc && gulp build",
     "promisetest": "gulp promisetest",
+    "promisefinallytest": "mocha promise.finally.spec.js",
     "webdriver-start": "webdriver-manager update && webdriver-manager start",
     "webdriver-http": "node simple-server.js",
     "webdriver-test": "node test/webdriver/test.js",
@@ -59,6 +60,7 @@
     "@types/jasmine": "2.2.33",
     "@types/node": "^6.0.96",
     "@types/systemjs": "^0.19.30",
+    "assert": "^1.4.1",
     "clang-format": "1.0.46",
     "concurrently": "^2.2.0",
     "conventional-changelog": "^1.1.7",