London | May-2026-itp | Vitalii Kmit | Sprint 3 | practice TDD coursework

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

@@ -1,5 +1,13 @@
 function countChar(stringOfCharacters, findCharacter) {
-  return 5
+  let count = 0;
+
+  for (const i of stringOfCharacters) {
+    if (i === findCharacter) {
+      count++;
+    }
+  }
+
+  return count;
 }
 
 module.exports = countChar;

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

@@ -22,3 +22,10 @@ test("should count multiple occurrences of a character", () => {
 // And a character `char` that does not exist within `str`.
 // When the function is called with these inputs,
 // Then it should return 0, indicating that no occurrences of `char` were found.
+test("should not find any occurrences", () => {
+  const str = "aaaaaaaa";
+  const char = "b";
+
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});

Sprint-3/2-practice-tdd/get-ordinal-number.js

@@ -1,5 +1,29 @@
 function getOrdinalNumber(num) {
-  return "1st";
+  if (typeof num !== "number" || Number.isNaN(num) || !Number.isInteger(num)) {
+    throw new Error(`Invalid type for ${num}, expected Number`);
+  }
+
+  const snum = String(num); // num as a string
+  const thList = ["11", "12", "13"]; // list of numbers that should end up with th as a suffix
+
+  const lastCharIndex = snum.length - 1;
+  const lastOne = snum[lastCharIndex];
+  const lastTwo = snum.slice(lastCharIndex - 1);
+
+  if (thList.includes(lastTwo)) {
+    return snum + "th";
+  }
+
+  switch (lastOne) {
+    case "1":
+      return snum + "st";
+    case "2":
+      return snum + "nd";
+    case "3":
+      return snum + "rd";
+    default:
+      return snum + "th";
+  }
 }
 
 module.exports = getOrdinalNumber;

Sprint-3/2-practice-tdd/get-ordinal-number.test.js

@@ -18,3 +18,66 @@ test("should append 'st' for numbers ending with 1, except those ending with 11"
   expect(getOrdinalNumber(21)).toEqual("21st");
   expect(getOrdinalNumber(131)).toEqual("131st");
 });
+
+test("should append 'nd' for numbers ending with 2, except those ending with 12", () => {
+  expect(getOrdinalNumber(2)).toEqual("2nd");
+  expect(getOrdinalNumber(22)).toEqual("22nd");
+  expect(getOrdinalNumber(132)).toEqual("132nd");
+});
+test("should append 'rd' for numbers ending with 3, except those ending with 13", () => {
+  expect(getOrdinalNumber(3)).toEqual("3rd");
+  expect(getOrdinalNumber(23)).toEqual("23rd");
+  expect(getOrdinalNumber(133)).toEqual("133rd");
+});
+test("should append 'th' for numbers ending with 0, 4-9, 10, 11, 12, 13", () => {
+  // 0
+  expect(getOrdinalNumber(0)).toEqual("0th");
+  expect(getOrdinalNumber(10)).toEqual("10th");
+  expect(getOrdinalNumber(100)).toEqual("100th");
+  // 4
+  expect(getOrdinalNumber(4)).toEqual("4th");
+  expect(getOrdinalNumber(24)).toEqual("24th");
+  expect(getOrdinalNumber(134)).toEqual("134th");
+
+  // 5
+  expect(getOrdinalNumber(5)).toEqual("5th");
+  expect(getOrdinalNumber(25)).toEqual("25th");
+  expect(getOrdinalNumber(135)).toEqual("135th");
+
+  // 6
+  expect(getOrdinalNumber(6)).toEqual("6th");
+  expect(getOrdinalNumber(26)).toEqual("26th");
+  expect(getOrdinalNumber(136)).toEqual("136th");
+
+  // 7
+  expect(getOrdinalNumber(7)).toEqual("7th");
+  expect(getOrdinalNumber(27)).toEqual("27th");
+  expect(getOrdinalNumber(137)).toEqual("137th");
+
+  // 8
+  expect(getOrdinalNumber(8)).toEqual("8th");
+  expect(getOrdinalNumber(28)).toEqual("28th");
+  expect(getOrdinalNumber(138)).toEqual("138th");
+
+  // 9
+  expect(getOrdinalNumber(9)).toEqual("9th");
+  expect(getOrdinalNumber(29)).toEqual("29th");
+  expect(getOrdinalNumber(139)).toEqual("139th");
+
+  // 10
+  expect(getOrdinalNumber(10)).toEqual("10th");
+  expect(getOrdinalNumber(100)).toEqual("100th");
+
+  //  11, 12, 13
+  expect(getOrdinalNumber(11)).toEqual("11th");
+  expect(getOrdinalNumber(12)).toEqual("12th");
+  expect(getOrdinalNumber(13)).toEqual("13th");
+});
+
+// edge cases
+test("should throw an error when given a wrong input type", () => {
+  expect(() => getOrdinalNumber("testing string")).toThrow("Invalid type for ");
+  expect(() => getOrdinalNumber("")).toThrow();
+  expect(() => getOrdinalNumber(null)).toThrow();
+  expect(() => getOrdinalNumber(undefined)).toThrow();
+});

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

@@ -1,7 +1,17 @@
-function repeatStr() {
+function repeatStr(str, 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) {
+    throw new Error("Expected a positive integer");
+  }
+
+  let out = "";
+
+  for (let i = 0; i < count; i++) {
+    out = out + str;
+  }
+
+  return out;
 }
 
 module.exports = repeatStr;

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

@@ -21,12 +21,31 @@ 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 with no repetitions", () => {
+  const str = "hello";
+  const count = 1;
+  const repeatedStr = repeatStr(str, count);
+  expect(repeatedStr).toEqual("hello");
+});
+
 // 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", () => {
+  const str = "hello";
+  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, as negative counts are not valid", () => {
+  const str = "hello";
+  const count = -1;
+  expect(() => repeatStr(str, count)).toThrow("Expected a positive integer");
+});