>>I have updated my answer
>
>I have a compiler warning (green underline) under this test
>
>

> public static Int32 Occurs(this String source, char pattern)
>      {
>         if (null==pattern)
>            return 0;
>         return source.Split(pattern).Length - 1;
>      }

>
>It is saying that value of type int never equals null.
>
>So, do I really need this test here for char?


No - I only mentioned for pattern = string