public async Task RetryHandler_CanRetry()
        {
            var apiResponse = new Mock <IAPIResponse <string> >();

            apiResponse.SetupGet(a => a.Body).Returns("Hello World");

            var response = new Mock <IResponse>();

            response.SetupGet(r => r.ContentType).Returns("application/json");
            response.SetupGet(r => r.StatusCode).Returns(HttpStatusCode.OK);
            response.SetupGet(r => r.Body).Returns("\"Hello World\"");

            var authenticator = new Mock <IAuthenticator>();
            var serializer    = new Mock <IJSONSerializer>();

            serializer.Setup(s => s.DeserializeResponse <string>(It.IsAny <IResponse>())).Returns(apiResponse.Object);

            var httpClient = new Mock <IHTTPClient>();

            httpClient.Setup(h => h.DoRequest(It.IsAny <IRequest>())).Returns(Task.FromResult(response.Object));

            var retryHandler = new Mock <IRetryHandler>();

            retryHandler.Setup(r =>
                               r.HandleRetry(
                                   It.IsAny <IRequest>(),
                                   It.IsAny <IResponse>(),
                                   It.IsAny <IRetryHandler.RetryFunc>()
                                   )
                               ).Returns((IRequest request, IResponse _, IRetryHandler.RetryFunc retry) => retry(request));

            var apiConnector = new APIConnector(
                new Uri("https://spotify.com"),
                authenticator.Object,
                serializer.Object,
                httpClient.Object,
                retryHandler.Object,
                null
                );
            await apiConnector.SendAPIRequest <string>(new Uri("/me", UriKind.Relative), HttpMethod.Get).ConfigureAwait(false);

            serializer.Verify(s => s.SerializeRequest(It.IsAny <IRequest>()), Times.Once);
            authenticator.Verify(a => a.Apply(It.IsAny <IRequest>(), It.IsAny <IAPIConnector>()), Times.Exactly(2));
            httpClient.Verify(h => h.DoRequest(It.IsAny <IRequest>()), Times.Exactly(2));
            serializer.Verify(s => s.DeserializeResponse <string>(response.Object), Times.Once);
        }