public async Task GetCustomGalleryAsync_DefaultParameters_NotNull()
        {
            var mockUrl      = "https://api.imgur.com/3/g/custom/viral/week/";
            var mockResponse = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(MockCustomGalleryEndpointResponses.GetCustomGallery)
            };

            var client   = new ImgurClient("123", "1234", MockOAuth2Token);
            var endpoint = new CustomGalleryEndpoint(client,
                                                     new HttpClient(new MockHttpMessageHandler(mockUrl, mockResponse)));
            var gallery = await endpoint.GetCustomGalleryAsync().ConfigureAwait(false);

            Assert.NotNull(gallery);
            Assert.Equal("imgurapidotnet", gallery.AccountUrl);
            Assert.Equal(60, gallery.ItemCount);
            Assert.Equal(60, gallery.Items.Count());
            Assert.Equal("http://imgur.com/custom", gallery.Link);
            Assert.Equal(2, gallery.Tags.Count());
        }
        public async Task GetCustomGalleryAsync_WithOAuth2TokenNull_ThrowsArgumentNullException()
        {
            var mockUrl      = "https://api.imgur.com/3/g/custom/top/month/1";
            var mockResponse = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(MockCustomGalleryEndpointResponses.GetCustomGallery)
            };

            var client   = new ImgurClient("123", "1234");
            var endpoint = new CustomGalleryEndpoint(client,
                                                     new HttpClient(new MockHttpMessageHandler(mockUrl, mockResponse)));

            var exception =
                await
                Record.ExceptionAsync(
                    async() =>
                    await
                    endpoint.GetCustomGalleryAsync(CustomGallerySortOrder.Top, TimeWindow.Month, 1)
                    .ConfigureAwait(false))
                .ConfigureAwait(false);

            Assert.NotNull(exception);
            Assert.IsType <ArgumentNullException>(exception);
        }