public void PatientMonthAgeAtSampling_ReturnsMonth(string birthDate, string samplingDate, string receivingDate, int?expectedAgeInMonth) { var isolate = new Isolate { Sending = new Sending { Patient = new Patient { BirthDate = DateTime.Parse(birthDate) }, SamplingDate = null, } }; if (!samplingDate.IsEmpty()) { isolate.Sending.SamplingDate = DateTime.Parse(samplingDate); } if (!receivingDate.IsEmpty()) { isolate.Sending.ReceivingDate = DateTime.Parse(receivingDate); } isolate.PatientMonthAgeAtSampling().Should().Be(expectedAgeInMonth); }