public void ApproxYobFromAgeTest()
{
SystemTime.NowFunction = () => new DateTime(2010, 6, 11, 10, 15, 16, 178);
// Null age
var expected = (int?)null;
var actual = DateTimeExtensions.ApproxYobFromAge(null);
Assert.IsNull(actual);
// Negative age
expected = null;
actual = DateTimeExtensions.ApproxAgeFromYob(-1);
Assert.IsNull(actual);
// Future yob
expected = null;
actual = DateTimeExtensions.ApproxAgeFromYob(2011);
Assert.IsNull(actual);
// Zero age
expected = 0;
actual = DateTimeExtensions.ApproxAgeFromYob(2010);
Assert.AreEqual(expected, actual);
// Future yob
expected = 3;
actual = DateTimeExtensions.ApproxAgeFromYob(2007);
Assert.AreEqual(expected, actual);
}