public override bool IsValid(object value)
{
var date = value as DateTime?;
var age = _ageCalculator.Age(date);
bool tooYoung = age < _minAge;
bool tooOld = age > _maxAge;
return(!tooYoung && !tooOld);
}
public void REturnsNullIfDateIsValid()
{
//Arrange & Act & Assert
Assert.AreEqual(null, AgeCalculator.Age(null));
}