public void GetFollowersTest()
        {
            // act

            _userRepositoryMock.Setup(x => x.GetChildren(It.IsAny<User>())).Returns(new List<User>
            {
                new User(),
                new User()
            });
            var userManager = new UserManager(_userRepositoryMock.Object);

            // actual
            var actual = userManager.GetFollowers(new User());

            // assert
            Assert.AreEqual(actual.Count(), 2);
        }