public void Count()
        {
            entityRepo.TruncateCollection();
            Assert.AreEqual(0, entityRepo.Count(), "Repo should be empty");

            var entity1 = TestHelper.GetEntity1();

            entityRepo.InsertOne(entity1);
            Assert.AreEqual(1, entityRepo.Count(), "Repo should contain one element");

            var entity2 = TestHelper.GetEntity2();

            entityRepo.InsertOne(entity2);
            Assert.AreEqual(2, entityRepo.Count(), "Repo should contain two elements");

            var entity3 = TestHelper.GetEntity3();
            var entity4 = TestHelper.GetEntity4();

            entityRepo.InsertMany(new List <TestEntity>()
            {
                entity3, entity4
            });
            Assert.AreEqual(4, entityRepo.Count(), "Repo should contain four elements");
        }