Test: add repeat.test.js to verify repeat function

- Added tests for repeat() covering:
  • repeating a string multiple times
  • returning empty string when count is 0
  • throwing error when count is negative
- Cleaned up unused code to follow best practices

Author: HoussamLh

Sprint-3/3-mandatory-practice/implement/repeat.test.js

@@ -0,0 +1,18 @@
+const repeat = require("./repeat");
+
+describe("repeat function tests", () => {
+
+  test("repeats string given number of times", () => {
+    expect(repeat("hi", 3)).toBe("hihihi");
+    expect(repeat("abc", 2)).toBe("abcabc");
+  });
+
+  test("returns empty string when count is 0", () => {
+    expect(repeat("hello", 0)).toBe("");
+  });
+
+  test("throws error if count is negative", () => {
+    expect(() => repeat("hi", -1)).toThrow("Count must be non-negative");
+  });
+
+});