public async Task AddBookForAuthorAsync_WithoutGuidBook_Test() { using (var context = new LibraryContext(Utilities.TestDbContextOptions())) using (ILibraryRepository repository = new LibraryRepository(context)) { context.Authors.Add(new Author() { Id = new Guid("a1da1d8e-1988-4634-b538-a01709477b77"), FirstName = "Jens", LastName = "Lapidus", Genre = "Thriller", DateOfBirth = new DateTimeOffset(new DateTime(1974, 5, 24)) }); context.SaveChanges(); await repository.AddBookForAuthorAsync( authorId : Guid.Parse("a1da1d8e-1988-4634-b538-a01709477b77"), book : new Book { Title = "Easy Money", Description = "Easy Money or Snabba cash is a novel from 2006 by Jens Lapidus." }); await repository.SaveChangesAsync(); var books = await repository.GetBooksForAuthorAsync(Guid.Parse("a1da1d8e-1988-4634-b538-a01709477b77")); Assert.Collection(books, bookItem => { Assert.Equal("Easy Money", bookItem.Title); Assert.Equal("Easy Money or Snabba cash is a novel from 2006 by Jens Lapidus.", bookItem.Description); }); } }