System.Text.UTF8Encoding.GetMaxCharCount C# (CSharp) Method

        public override int GetMaxCharCount(int byteCount)
        {
            throw null;
        }

 public void NegTest1()
 {
     UTF8Encoding utf8 = new UTF8Encoding();
     int byteCount = -1;
     Assert.Throws<ArgumentOutOfRangeException>(() =>
     {
         int maxCharCount = utf8.GetMaxCharCount(byteCount);
     });
 }