public async Task ConvertDocumentToTextAsync_NullFile_ThrowsArgumentNullException()
        {
            var service = new DocumentConversionService("username", "password", new WatsonSettings());

            var exception =
                await
                    Record.ExceptionAsync(
                        async () => await service.ConvertDocumentToTextAsync(null, FileType.Xml).ConfigureAwait(false))
                        .ConfigureAwait(false);
            Assert.NotNull(exception);
            Assert.IsType<ArgumentNullException>(exception);
        }
        public async Task ConvertDocumentToTextAsync()
        {
            var mockHttpMessageHandler = new MockHttpMessageHandler();
            var mockResponse = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(MockDocumentConversionResponses.MockTextResponse)
            };

            mockHttpMessageHandler.AddResponseMessage(ServiceUrl, mockResponse);

            var httpCLient = new HttpClient(mockHttpMessageHandler);

            var service = new DocumentConversionService("username", "password", httpCLient, new WatsonSettings());
            var actual =
                await service.ConvertDocumentToTextAsync(new MemoryStream(), FileType.Html).ConfigureAwait(false);

            Assert.Equal(MockDocumentConversionResponses.MockTextResponse, actual);
        }