public async Task RegexNotMatchTest()
        {
            var service = new SimpleThumbnailService(@"http://example.com/(.+)", @"http://img.example.com/\1");

            var thumbinfo = await service.GetThumbnailInfoAsync("http://hogehoge.com/abcd", null, CancellationToken.None);

            Assert.Null(thumbinfo);
        }
        public async Task RegexMatchTest()
        {
            var service = new SimpleThumbnailService(@"http://example.com/(.+)", @"http://img.example.com/$1");

            var thumbinfo = await service.GetThumbnailInfoAsync("http://example.com/abcd", null, CancellationToken.None);

            Assert.NotNull(thumbinfo);
            Assert.Equal("http://example.com/abcd", thumbinfo.ImageUrl);
            Assert.Equal("http://img.example.com/abcd", thumbinfo.ThumbnailUrl);
            Assert.Null(thumbinfo.TooltipText);
        }