                     onNext: { (group: GroupedObservable<String, String>) -> Void in
                         outerResults.onNext(group.key)
                         
-                        let result: MockObserver<String> = scheduler.createObserver(String)
+                        let result: TestableObserver<String> = scheduler.createObserver(String)
                         inners[group.key] = group
                         results[group.key] = result
                         innerSubscriptions[group.key] = group.subscribe(result)

        var outerSubscription: Disposable?
        var inners = Dictionary<String, GroupedObservable<String, String>>()
        var innerSubscriptions = Dictionary<String, Disposable>()
        var results = Dictionary<String, MockObserver<String>>()
        
        scheduler.scheduleAt(Defaults.subscribed) {
            let outer: Observable<GroupedObservable<String, String>> = xs.groupBy { x in

            error(570, testError)
            ])
        
        let results: TestableObserver<String> = scheduler.createObserver(String)
        var outer: Observable<GroupedObservable<String, String>>?
        var outerSubscription: Disposable?
        var inner: GroupedObservable<String, String>?
