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

        public override int GetMaxByteCount(int charCount)
        {
            throw null;
        }

 public void NegTest1()
 {
     UTF8Encoding utf8 = new UTF8Encoding();
     int charCount = -1;
     Assert.Throws<ArgumentOutOfRangeException>(() =>
     {
         int maxByteCount = utf8.GetMaxByteCount(charCount);
     });
 }