public void TestAny()
        {
            const bool result = true;
            //create root node
            var root = new JoinNode(typeof(Products));

            // add child node Categories with propertyName "Products".
            // Because Categories linked with Products by next property:
            // public EntitySet<Products> Products
            root.AddChildren(new JoinNode(typeof(Categories), "Category", "Products"));

            var queryDesinger = new QueryDesigner(context, root);
            var any = queryDesinger.Any();

            // check numbers of entity
            Assert.AreEqual(result, any);
        }