public async void RatingRepository_Post_NullRating_Failure() { RatingEntry _rating = null; _mockContext.Setup(p => p.RatingsCollectionName).Returns("ratings"); _mockContext.Setup(p => p.ConnectionString).Returns("mongodb://localhost:27017"); _mockContext.Setup(p => p.DatabaseName).Returns("RatingDB"); var ratingRepository = new RatingRepository(_mockContext.Object); await Assert.ThrowsAsync <ArgumentNullException>(() => ratingRepository.AddRating(_rating)); }