public async Task ReturnsNullIfNotFound()
            {
                var authorId = -1;
                var author   = await AuthorsEndpoint.GetByAuthorId(authorId);

                Assert.Null(author);
            }
            public async Task ReturnsAnAuthor()
            {
                var authorId = 38550;
                var author   = await AuthorsEndpoint.GetByAuthorId(authorId);

                Assert.NotNull(author);
                Assert.Equal(author.Id, authorId);
            }