public async Task AddPhotoComment_PopulatesInputProperly()
        {
            UserId       userId               = new Guid("13999be1-095a-4726-87e9-d11f2103585c");
            PhotoId      photoId              = new Guid("d3f31301-c244-4104-9b83-2ad073a8d2d0");
            string       userName             = "******";
            string       text                 = "not empty";
            PhotoComment observedPhotoComment = null;

            // set up expectation that AddPhotoComment is invoked in the data repository
            commentRepositoryMock
            .Setup(x => x.AddPhotoComment(It.IsAny <PhotoComment>()))
            .Callback <PhotoComment>(x => observedPhotoComment = x)
            .Returns(Task.CompletedTask);

            var service = GetFeedbackService();


            await service.AddPhotoComment(photoId, userId, userName, text);

            observedPhotoComment.ShouldNotBeNull();
            observedPhotoComment.PhotoId.ShouldBe(photoId);
            observedPhotoComment.UserId.ShouldBe(userId);
            observedPhotoComment.UserName.ShouldBe(userName);
            observedPhotoComment.Text.ShouldBe(text);
        }