String helper: Truncate with ellipsis

gistfile1.cs

public static string Truncate(this string s, int maxLength, bool withEllipsis = false)
{
    if (maxLength < 0) throw new ArgumentOutOfRangeException(nameof(maxLength), "must be at least zero");
    if (s == null || s.Length <= maxLength) return s;
    if (withEllipsis && maxLength > 3)
    {
        return s.Substring(0, maxLength - 3) + "...";
    }
    return s.Substring(0, maxLength);
}

//[Test]
//public void TruncateTests()
//{
//    Assert.IsNull((null as string).Truncate(10));
//    Assert.Throws<ArgumentOutOfRangeException>(() => "blah".Truncate(-1));
//    Assert.AreEqual("", "blah".Truncate(0));
//    Assert.AreEqual("", "blah".Truncate(0, withEllipsis: true));
//    Assert.AreEqual("b", "blah".Truncate(1));
//    Assert.AreEqual("b", "blah".Truncate(1, withEllipsis: true));
//    Assert.AreEqual("bl", "blah".Truncate(2));
//    Assert.AreEqual("bl", "blah".Truncate(2, withEllipsis: true));
//    Assert.AreEqual("bla", "blah".Truncate(3));
//    Assert.AreEqual("bla", "blah".Truncate(3, withEllipsis: true));
//    Assert.AreEqual("blah", "blah".Truncate(4));
//    Assert.AreEqual("blah", "blah".Truncate(4, withEllipsis: true));
//    Assert.AreEqual("blah", "blah".Truncate(5));
//    Assert.AreEqual("blah", "blah".Truncate(5, withEllipsis: true));
//    Assert.AreEqual("blah", "blahsdvsdv".Truncate(4));
//    Assert.AreEqual("b...", "blahsdvsdv".Truncate(4, withEllipsis: true));
//}