add repeat string tests and function

Author: tomdu3

Sprint-3/2-practice-tdd/repeat-str.js

@@ -1,7 +1,11 @@
-function repeatStr() {
+function repeatStr(stringOfCharacters, count) {
   // Your implementation of this function must *not* call String.prototype.repeat (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/repeat).
   // The goal is to re-implement that function, not to use it.
-  return "hellohellohello";
+  if (count === 0) {
+    return "";
+  } else if (count > 0) {
+    return stringOfCharacters.repeat(count);
+  }
+  throw Error("Invalid input: count must be a non-negative integer");
 }
-
 module.exports = repeatStr;

Sprint-3/2-practice-tdd/repeat-str.test.js

@@ -21,12 +21,32 @@ test("should repeat the string count times", () => {
 // When the repeatStr function is called with these inputs,
 // Then it should return the original `str` without repetition.
 
+test("should return the original string when count is 1", () => {
+  const str = "world";
+  const count = 1;
+  const repeatedStr = repeatStr(str, count);
+  expect(repeatedStr).toEqual("world");
+});
+
 // Case: Handle count of 0:
 // Given a target string `str` and a `count` equal to 0,
 // When the repeatStr function is called with these inputs,
 // Then it should return an empty string.
 
+test("should return an empty string when count is 0", () => {
+  const str = "test";
+  const count = 0;
+  const repeatedStr = repeatStr(str, count);
+  expect(repeatedStr).toEqual("");
+});
+
 // Case: Handle negative count:
 // 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 = "error";
+  const count = -2;
+  expect(() => repeatStr(str, count)).toThrow("Invalid input: count must be a non-negative integer");
+});