public void ShouldGetLatestTargetDate()
        {
            //Given
            var date = new DateTime(2018, 1, 2);

            _healthRepository.Setup(x => x.GetLatestTargetDate()).Returns(date);

            //when
            var latestDate = _healthService.GetLatestTargetDate(DateTime.MinValue);

            //then
            Assert.Equal(date, latestDate);
        }