public async Task AddCommentShouldIncreaseCommentCount() { // Arrange var db = this.GetDatabase(); var user = new User { Id = "admin", Email = "*****@*****.**" }; var firstArticle = new Article { Id = 1, Title = "First article", Content = new String('p', 255) }; var articleComment = new ArticleComment { ArticleId = 1, Content = "Asd", Author = user, AuthorId = "admin" }; await db.Articles.AddAsync(firstArticle); await db.Comments.AddAsync(articleComment); await db.SaveChangesAsync(); var articleService = new ArticleService(db); // Act var result = articleService.AddCommentAsync(firstArticle.Id, articleComment.Content, user.Id); // Assert firstArticle .Comments .Count .Should() .Be(2); }