public async Task GetSimpleListReturnsNullWhenError() { // arrange const HttpStatusCode expectedStatusCode = HttpStatusCode.NotFound; IEnumerable <SimpleJobProfileModel> expectedResults = null; var httpResponse = new HttpResponseMessage { StatusCode = expectedStatusCode, Content = new StringContent(JsonConvert.SerializeObject(expectedResults)) }; var fakeHttpRequestSender = A.Fake <IFakeHttpRequestSender>(); var fakeHttpMessageHandler = new FakeHttpMessageHandler(fakeHttpRequestSender); using (var httpClient = new HttpClient(fakeHttpMessageHandler)) { var refreshService = new RefreshService(httpClient, fakeLogger, fakeRefreshClientOptions); A.CallTo(() => fakeHttpRequestSender.Send(A <HttpRequestMessage> .Ignored)).Returns(httpResponse); // act var results = await refreshService.GetListAsync().ConfigureAwait(false); // assert Assert.Equal(expectedResults, results); } httpResponse.Dispose(); fakeHttpMessageHandler.Dispose(); }