public void ReturnCorrectFriendsIds()
        {
            // Arrange
            int userId = 10;
            var mockedUserFriendRepository = new Mock <IEFRepository <UserFriend> >();
            var friendShips = new List <UserFriend>()
            {
                new UserFriend()
                {
                    UserId = userId, FriendId = 2
                },
                new UserFriend()
                {
                    UserId = 50, FriendId = 1
                },
                new UserFriend()
                {
                    UserId = userId, FriendId = 3
                }
            }.AsQueryable();

            mockedUserFriendRepository.Setup(x => x.All).Returns(friendShips);
            var mockedUserRepository    = new Mock <IEFRepository <CustomUser> >();
            var mockedUserFriendFactory = new Mock <IUserFriendFactory>();
            var mockedUnitOfWork        = new Mock <IUnitOfWork>();

            var friendService = new FriendService(
                mockedUserFriendRepository.Object,
                mockedUserRepository.Object,
                mockedUserFriendFactory.Object,
                mockedUnitOfWork.Object);
            var expected = new List <int>()
            {
                2, 3
            };

            // Act
            var result = friendService.GetAllUserFriendsIds(userId);

            // Assert
            CollectionAssert.AreEqual(result, expected);
        }