--- /dev/null
+import { Observable } from '../Observable';
+import { ObservableInput } from '../types';
+
+/**
+ * Tests to see if the object is an RxJS {@link Observable}
+ * @param obj the object to test
+ */
+export function isObservable<T>(obj: any): obj is Observable<T> {
+ return !!obj && (obj instanceof Observable || (typeof obj.lift === 'function' && typeof obj.subscribe === 'function'));
+}