added a comment

Author: mshayriyesaricicek

Sprint-3/2-practice-tdd/count.test.js

@@ -57,3 +57,8 @@ test("should count multiple occurrences of a character", () => {
   const count = countChar(str, char);
   expect(count).toEqual(4);
 });
+
+//handling invalid input
+//the tests work assuming that only letters are in the string - no numbers or special characters
+
+