YesSql.Tests.CoreTests.UpdatingDocumentShouldUpdateReducedIndex C# (CSharp) Method

        public async Task UpdatingDocumentShouldUpdateReducedIndex()
        {
            _store.RegisterIndexes<ArticleIndexProvider>();

            using (var session = _store.CreateSession())
            {
                var dates = new[]
                {
                    new DateTime(2011, 11, 1),
                    new DateTime(2011, 11, 1),
                    new DateTime(2011, 11, 1),
                    new DateTime(2011, 11, 1),

                    new DateTime(2011, 11, 2),
                    new DateTime(2011, 11, 2),
                    new DateTime(2011, 11, 2),

                    new DateTime(2011, 11, 3),
                    new DateTime(2011, 11, 3),

                    new DateTime(2011, 11, 4)
                };

                foreach (var date in dates)
                {
                    session.Save(new Article { PublishedUtc = date });
                }

            }

            using (var session = _store.CreateSession())
            {
                // 10 articles
                Assert.Equal(10, await session.QueryAsync().For<Article>().Count());

                // 4 indexes as there are 4 different dates
                Assert.Equal(4, await session.QueryIndexAsync<ArticlesByDay>().Count());
            }

            // change the published date of an article
            using (var session = _store.CreateSession())
            {
                var article = await session
                    .QueryAsync<Article, ArticlesByDay>()
                    .Where(b => b.DayOfYear == new DateTime(2011, 11, 2).DayOfYear)
                    .FirstOrDefault();

                Assert.NotNull(article);

                article.PublishedUtc = new DateTime(2011, 11, 3);

                session.Save(article);

            }

            // there should be the same number of indexes
            using (var session = _store.CreateSession())
            {
                Assert.Equal(10, await session.QueryAsync().For<Article>().Count());
                Assert.Equal(4, await session.QueryIndexAsync<ArticlesByDay>().Count());

                Assert.Equal(4, await session.QueryAsync<Article, ArticlesByDay>(x => x.DayOfYear == new DateTime(2011, 11, 1).DayOfYear).Count());
                Assert.Equal(2, await session.QueryAsync<Article, ArticlesByDay>(x => x.DayOfYear == new DateTime(2011, 11, 2).DayOfYear).Count());
                Assert.Equal(3, await session.QueryAsync<Article, ArticlesByDay>(x => x.DayOfYear == new DateTime(2011, 11, 3).DayOfYear).Count());
                Assert.Equal(1, await session.QueryAsync<Article, ArticlesByDay>(x => x.DayOfYear == new DateTime(2011, 11, 4).DayOfYear).Count());
            }
        }