public void TestGetAllFollowingId()
        {
            mockFollowRepository.Setup(x => x.GetAllFollowingId(It.IsAny <string>())).Returns(getAllFollowingId);
            var           followService           = new FollowService(mockFollowRepository.Object);
            List <string> getAllFollowingIds      = followService.GetAllFollowingId("5d111299f3b75e0001f4ed78");
            string        followeingIdFirstActual = getAllFollowingIds.FirstOrDefault();

            Assert.AreEqual(followeingIdFirstActual, "5d0a17701a0a4200017de6cv");
        }