public async Task Update_Book_Genres()
{
var book = await BookHelpers.CreateValidBookWithAllProperties();
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.Genres.Count.Should().Be(2);
var genre1 = await GenreHelpers.CreateValidGenre();
var genre2 = await GenreHelpers.CreateValidGenre();
var genres = new List <Genre> {
genre1, genre2
};
await BookHelpers.UpdateGenres(sut.Id, genres);
sut = await repository.LoadAsync(book.Id);
await _fixture.Context.Entry(sut).ReloadAsync();
sut.Genres.Count.Should().Be(4);
sut.Id.Should().Be(bookId);
}