public void GetYears_Should_Return_Age_When_Dob_Is_Valid(string dob)
{
_premiumService = new PremiumService();
var age = _premiumService.GetYears(dob);
Assert.IsNotNull(age);
}
public void GetYears_Should_Throw_Exception_When_Input_Is_Nll()
{
_premiumService = new PremiumService();
Assert.Throws <ArgumentNullException>(() => _premiumService.GetYears(null));
}