public async Task SetAsyncAddsNewItem()
        {
            // arrange
            using var scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled);
            var item = new CoursePath(Guid.NewGuid(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid());

            // act
            var repository = new CoursePathRepository(_database.SqlServerRepositoryOptions);
            var result     = await repository.SetAsync(item).ConfigureAwait(false);

            // assert
            using var connection = new SqlConnection(_database.ConnectionString);
            var saved = await connection.QuerySingleOrDefaultAsync <CoursePath>("SELECT [Key], [Name], [Slug], [Version] FROM [dbo].[CoursePath] WHERE [Key] = @Key", new { item.Key }).ConfigureAwait(false);

            // assert - result equals input except version
            Assert.Equal(result.Key, item.Key);
            Assert.Equal(result.Name, item.Name);
            Assert.Equal(result.Slug, item.Slug);
            Assert.NotEqual(result.Version, item.Version);

            // assert - saved equals input except version
            Assert.Equal(saved.Key, item.Key);
            Assert.Equal(saved.Name, item.Name);
            Assert.Equal(saved.Slug, item.Slug);
            Assert.NotEqual(saved.Version, item.Version);

            // assert - result version equals saved version
            Assert.Equal(saved.Version, result.Version);
        }
        public async Task SetAsyncUpdatesExistingItem()
        {
            // arrange
            using (new TransactionScope(TransactionScopeAsyncFlowOption.Enabled))
            {
                var item = new CoursePath(Guid.NewGuid(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid());
                using (var connection = new SqlConnection(_database.ConnectionString))
                {
                    await connection.ExecuteAsync("INSERT INTO [dbo].[CoursePath] ([Key], [Name], [Slug], [Version]) VALUES (@Key, @Name, @Slug, @Version)", item).ConfigureAwait(false);
                }

                // act
                var repository = new CoursePathRepository(_database.SqlServerRepositoryOptions);
                var current    = await repository.GetAsync(item.Key).ConfigureAwait(false);

                var proposed = new CoursePath(current.Key, Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), current.Version);
                var saved    = await repository.SetAsync(proposed).ConfigureAwait(false);

                // assert
                using (var connection = new SqlConnection(_database.ConnectionString))
                {
                    var actual = await connection.QuerySingleOrDefaultAsync <CoursePath>("SELECT [Key], [Name], [Slug], [Version] FROM [dbo].[CoursePath] WHERE [Key] = @Key", new { item.Key }).ConfigureAwait(false);

                    // assert - current equals item
                    Assert.Equal(item, current);

                    // assert - actual equals saved
                    Assert.Equal(saved, actual);

                    // assert - saved equals proposed plus new version
                    Assert.Equal(proposed.Key, saved.Key);
                    Assert.Equal(proposed.Name, saved.Name);
                    Assert.Equal(proposed.Slug, saved.Slug);
                    Assert.NotEqual(proposed.Version, saved.Version);
                }
            }
        }
        public async Task SetAsyncThrowsOnExistingSlug()
        {
            // arrange
            using var scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled);
            var existing = new CoursePath(Guid.NewGuid(), Guid.NewGuid().ToString(), Guid.NewGuid().ToString(), Guid.NewGuid());

            await using (var connection = new SqlConnection(_database.ConnectionString))
            {
                await connection.ExecuteAsync("INSERT INTO [dbo].[CoursePath] ([Key], [Name], [Slug], [Version]) VALUES (@Key, @Name, @Slug, @Version)", existing).ConfigureAwait(false);
            }

            // act
            var item       = new CoursePath(Guid.NewGuid(), Guid.NewGuid().ToString(), existing.Slug, Guid.NewGuid());
            var repository = new CoursePathRepository(_database.SqlServerRepositoryOptions);
            var ex         = await Assert.ThrowsAsync <SlugAlreadyExistsException>(() => repository.SetAsync(item)).ConfigureAwait(false);

            // assert
            Assert.Equal(existing.Slug, ex.Slug);
        }