public async Task Update_Book_Publisher()
{
var book = await BookHelpers.CreateValidBook();
var repository = new BookRepository(_fixture.Context);
(await repository.ExistsAsync(book.Id)).Should().BeTrue();
var sut = await repository.LoadAsync(book.Id);
var bookId = sut.Id;
sut.Should().NotBeNull();
sut.Publisher.Should().BeNull();
var publisher = await PublisherHelpers.CreateValidPublisher();
await BookHelpers.UpdatePublisher(sut.Id, publisher);
sut = await repository.LoadAsync(book.Id);
await _fixture.Context.Entry(sut).ReloadAsync();
sut.Publisher.Id.Should().Be(publisher.Id);
sut.Publisher.Name.Should().Be(publisher.Name);
sut.Id.Should().Be(bookId);
}