Add test for negative count in repeat-str

Author: lwandogwele52-ui

practice-tdd/repeat-str.test.js

@@ -40,3 +40,8 @@ test("should return an empty string when count is 0", () => {
 // Given a target string `str` and a negative integer `count`,
 // When the repeatStr function is called with these inputs,
 // Then it should throw an error, as negative counts are not valid.
+test("should throw an error when count is negative", () => {
+  const str = "hello";
+  const count = -1;
+  expect(() => repeatStr(str, count)).toThrow();
+});