public void Addition_Subtraction(int leftDays, long leftNanos,
int rightDays, long rightNanos,
int resultDays, long resultNanos)
{
var left = new Duration(leftDays, leftNanos);
var right = new Duration(rightDays, rightNanos);
var result = new Duration(resultDays, resultNanos);
Assert.AreEqual(result, left + right);
Assert.AreEqual(result, left.Plus(right));
Assert.AreEqual(result, Duration.Add(left, right));
Assert.AreEqual(left, result - right);
Assert.AreEqual(left, result.Minus(right));
Assert.AreEqual(left, Duration.Subtract(result, right));
}