fix(forkJoin): fix forkJoin to complete if sources Array is empty.

Author: trxcllnt

spec/observables/forkJoin-spec.js

@@ -169,6 +169,13 @@ describe('Observable.forkJoin', function () {
     expectObservable(e1).toBe(expected);
   });
 
+  it('should complete if sources list is empty', function () {
+    var e1 = Observable.forkJoin([]);
+    var expected = '|';
+
+    expectObservable(e1).toBe(expected);
+  });
+
   it('should complete when any of source is empty with selector', function () {
     function selector(x, y) {
       return x + y;
@@ -242,4 +249,4 @@ describe('Observable.forkJoin', function () {
 
     expectObservable(e1).toBe(expected);
   });
-});
+});

src/observable/forkJoin.ts

@@ -29,6 +29,10 @@ export class ForkJoinObservable<T> extends Observable<T> {
       sources = <Array<Observable<any>>>sources[0];
     }
 
+    if (sources.length === 0) {
+      return new EmptyObservable<T>();
+    }
+
     return new ForkJoinObservable(<Array<Observable<any> | Promise<any>>>sources, resultSelector);
   }