public void WhenAddMillisecondsCalled_ExpectSameValueReturned()
{
// Arrange
var now = DateTime.Now;
const int added = 15;
var expected = now.AddMilliseconds(added);
// Act
var target = new DateTimeWrap(now);
var actual = target.AddMilliseconds(added);
// Assert
actual.DateTimeInstance.Should().Equal(expected);
}