public async Task LogoutCall_Test()
        {
            IHttpService     httpService    = A.Fake <IHttpService>();
            IEventAggregator evenAggregator = A.Fake <IEventAggregator>();

            httpService = A.Fake <IHttpService>();
            ServerListViewModel serverListViewModel = new ServerListViewModel(evenAggregator, httpService);

            await serverListViewModel.Servers();

            A.CallTo(() => httpService.GetAsync <List <Server> >(A <string> ._, A <string> ._)).MustHaveHappened();
        }