Add test for new when signature

q/Q-tests.ts

@@ -94,6 +94,7 @@ Q.fbind((dateString?: string) => new Date(dateString), "11/11/1991")().then(d =>
 
 Q.when(8, num => num + "!");
 Q.when(Q(8), num => num + "!").then(str => str.split(','));
+var voidPromise: Q.Promise<void> = Q.when();
 
 declare function saveToDisk(): Q.Promise<any>;
 declare function saveToCloud(): Q.Promise<any>;