diff --git a/spec/helpers/test-helper.ts b/spec/helpers/test-helper.ts
index b6cea52885..75477dcd1a 100644
--- a/spec/helpers/test-helper.ts
+++ b/spec/helpers/test-helper.ts
@@ -17,6 +17,7 @@ global.hot = marbleHelpers.hot;
 global.time = marbleHelpers.time;
 global.expectObservable = marbleHelpers.expectObservable;
 global.expectSubscriptions = marbleHelpers.expectSubscriptions;
+global.type = type;
 
 //amending type definition of jasmine which seems doesn't have this
 export interface DoneSignature {
@@ -77,6 +78,11 @@ if (!global.asDiagram) {
   global.asDiagram = asDiagram;
 }
 
+export function type(assertion: Function): void {
+  //intentionally does not execute to avoid unexpected side effect occurs by subscription,
+  //or infinite source. Suffecient to check build time only.
+}
+
 export function lowerCaseO<T>(...args): Rx.Observable<T> {
   const values = [].slice.apply(arguments);
 
@@ -154,4 +160,4 @@ global.__root__ = root;
 
 afterEach(function () {
   global.rxTestScheduler = null;
-});
\ No newline at end of file
+});
diff --git a/spec/operators/toArray-spec.ts b/spec/operators/toArray-spec.ts
index e5ae454c22..1d4baf891d 100644
--- a/spec/operators/toArray-spec.ts
+++ b/spec/operators/toArray-spec.ts
@@ -1,5 +1,5 @@
 import * as Rx from '../../dist/cjs/Rx';
-declare const {hot, cold, asDiagram, expectObservable, expectSubscriptions};
+declare const {hot, cold, asDiagram, expectObservable, expectSubscriptions, type};
 
 const Observable = Rx.Observable;
 
@@ -101,4 +101,12 @@ describe('Observable.prototype.toArray', () => {
     expectObservable(e1.toArray()).toBe(expected);
     expectSubscriptions(e1.subscriptions).toBe(e1subs);
   });
+
+  type(() => {
+    const typeValue = {
+      val: 3
+    };
+
+    Observable.of(typeValue).toArray().subscribe(x => { x[0].val.toString(); });
+  });
 });