public void EditReview()
        {
            // Arrange:
            int userId    = 9;
            int bookId    = 9;
            var newReview = new BookReviewViewModel
            {
                Rating = 4,
                Review = "geggjud bok"
            };
            var prevCountAll  = _reviewService.GetAllBookReviewsForAllBooks().Sum(i => i.Reviews.Count());
            var prevCountUser = _reviewService.GetAllUserReviews(userId).Count();
            var prevCountBook = _reviewService.GetAllBookReviews(bookId).Count();

            // Act:
            _reviewService.EditReview(userId, bookId, newReview);

            // Assert:

            // Ensure that a new entity object has been updated and not just added to the list:
            var currentCountAll  = _reviewService.GetAllBookReviewsForAllBooks().Sum(i => i.Reviews.Count());
            var currentCountUser = _reviewService.GetAllUserReviews(userId).Count();
            var currentCountBook = _reviewService.GetAllBookReviews(bookId).Count();

            Assert.AreEqual(prevCountAll, currentCountAll);
            Assert.AreEqual(prevCountUser, currentCountUser);
            Assert.AreEqual(prevCountBook, currentCountBook);

            // Get access to the entity object and assert that
            // the properties have been set:
            var newEntity = _reviewService.GetUserReview(userId, bookId);

            Assert.AreEqual(8, newEntity.BookReviewId);
            Assert.AreEqual("9title", newEntity.BookTitle);
            Assert.AreEqual(4, newEntity.Rating);
            Assert.AreEqual("geggjud bok", newEntity.Review);
            Assert.AreEqual(new DateTime(1988, 10, 2), newEntity.DateOfReview);
        }