public void TestRelations()
        {
            Helper.DropAllCollections();

            var c = new Country {Code = "ES", Name = "España"};
            c.Save();
            c = new Country {Code = "UK", Name = "Reino Unido"};
            c.Save();

            var p = new Person
                {
                    Name = "Pepito Perez",
                    Age = 35,
                    BirthDate = DateTime.Now.AddDays(57).AddYears(-35),
                    Married = true,
                    Country = "XXXXX",
                    BankBalance = decimal.Parse("3500,00")
                };

            p.Childs.Add(
                new Child {ID = 1, Age = 10, BirthDate = DateTime.Now.AddDays(57).AddYears(-10), Name = "Juan Perez"});
            p.Childs.Add(
                new Child {ID = 2, Age = 7, BirthDate = DateTime.Now.AddDays(57).AddYears(-7), Name = "Ana Perez"});

            try
            {
                p.Save();
            }
            catch (Exception ex)
            {
                Assert.AreEqual(ex.GetBaseException().GetType(), typeof (ValidateUpRelationException));
                p.Country = "ES";
                p.Save();
            }

            c = MongoMapper.FindByKey<Country>("ES");
            try
            {
                c.Delete();
            }
            catch (Exception ex)
            {
                Assert.AreEqual(ex.GetBaseException().GetType(), typeof (ValidateDownRelationException));
                List<Person> Persons = c.GetRelation<Person>("Person,Country");
                foreach (Person p2 in Persons)
                {
                    p2.Country = "UK";
                    p2.Save();
                }
                c.Delete();
            }

            c = MongoMapper.FindByKey<Country>("UK");

            List<Person> PersonasEnUK = c.GetRelation<Person>("Person,Country");
            foreach (Person PersonInUK in PersonasEnUK)
            {
                Assert.AreEqual(PersonInUK.Country, "UK");
                Assert.AreEqual(PersonInUK.GetRelation<Country>("Country,Code").First().Code, "UK");
            }
        }