Implement countChar, repeatStr, and getOrdinalNumber functions with TDD

Author: fromonda

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

@@ -1,5 +1,13 @@
 function countChar(stringOfCharacters, findCharacter) {
-  return 5
+  let count = 0;
+
+  for (const char of stringOfCharacters) {
+    if (char === 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 count no occurrences of a character", () => {
+  const str = "aaaaa";
+  const char = "b";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});

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

@@ -1,5 +1,21 @@
 function getOrdinalNumber(num) {
-  return "1st";
+  if (num % 10 === 1) {
+    return `${num}st`;
+  }
+
+  if (num % 10 === 2) {
+    return `${num}nd`;
+  }
+
+  if (num % 10 === 3) {
+    return `${num}rd`;
+  }
+
+  if (num % 100 === 11 || num % 100 === 12 || num % 100 === 13) {
+    return `${num}th`;
+  }
+
+  return `${num}th`;
 }
 
 module.exports = getOrdinalNumber;

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

@@ -18,3 +18,15 @@ 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(102)).toEqual("102nd");
+});
+
+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(103)).toEqual("103rd");
+});

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

@@ -1,7 +1,15 @@
 function repeatStr() {
-  // 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("invalid");
+  }
+
+  let result = "";
+
+  for (let i = 0; i < count; i++) {
+    result += str;
+  }
+
+  return result;
 }
 
 module.exports = repeatStr;

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

@@ -21,12 +21,33 @@ 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 repeat the string 1 time", () => {
+  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 not repeat the 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 for negative count", () => {
+  const str = "hello";
+  const count = -1;
+  const repeatedStr = repeatStr(str, count);
+  expect(() => repeatStr(str, count)).toThrow();
+});