London | 26-ITP-Sep | Chandramani Gaire | Sprint 2 | Practice tdd

practice-tdd/README.md

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+# Practice TDD
+
+In this section you'll practice this key skill of building up your program test first.
+
+Use the Jest syntax and complete the provided files, meeting the acceptance criteria for each function. Use the VSCode test runner to run your tests and check your progress.
+
+Write the tests _before_ the code that will make them pass.
+
+Recommended order:
+
+1. `count.test.js`
+1. `repeat-str.test.js`
+1. `get-ordinal-number.test.js`

practice-tdd/count.js

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+export function countChar(stringOfCharacters, findCharacter) {
+  let count = 0;
+  for (let i = 0; i < stringOfCharacters.length; i++) {
+    if (stringOfCharacters[i] === findCharacter) {
+      count++;
+    }
+  }
+  return count;
+}
+console.log(countChar("helo", "a"));

practice-tdd/count.test.js

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+// implement a function countChar that counts the number of times a character occurs in a string
+import { countChar } from "./count.js";
+// Given a string `str` and a single character `char` to search for,
+// When the countChar function is called with these inputs,
+// Then it should:
+
+// Scenario: Multiple Occurrences
+// Given the input string `str`,
+// And a character `char` that occurs one or more times in `str` (e.g., 'a' in 'aaaaa'),
+// When the function is called with these inputs,
+// Then it should correctly count occurrences of `char`.
+
+test("should count multiple occurrences of a character", () => {
+  const str = "aaaaa";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(5);
+});
+test("should count multiple occurrences of a character mixed with other characters", () => {
+  const str = "banana";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(3);
+});
+
+test("should return 1 when the character appears exactly once", () => {
+  const str = "hello";
+  const char = "h";
+  const count = countChar(str, char);
+  expect(count).toEqual(1);
+});
+
+test("should count non-adjacent occurrences of a character", () => {
+  const str = "abcabca";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(3);
+});
+
+test("should count spaces and special characters", () => {
+  const str = "a b c";
+  const char = " ";
+  const count = countChar(str, char);
+  expect(count).toEqual(2);
+});
+
+// Scenario: No Occurrences
+// Given the input string `str`,
+// 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 return 0 when there is not repeated char in str", () => {
+  const str = "hello";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});
+test("should be case-sensitive", () => {
+  const str = "Apple";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});
+test("should return 0 when str is an empty string", () => {
+  const str = "";
+  const char = "a";
+  const count = countChar(str, char);
+  expect(count).toEqual(0);
+});

practice-tdd/get-ordinal-number.js

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+export function getOrdinalNumber(num) {
+  const lastTwoDigit = num % 100;
+  const lastDigit = num % 10;
+  if (lastTwoDigit >= 11 && lastTwoDigit <= 13) {
+    return `${num}th`;
+  }
+  if (lastDigit === 1) {
+    return `${num}st`;
+  }
+  if (lastDigit === 2) {
+    return `${num}nd`;
+  }
+  if (lastDigit === 3) {
+    return `${num}rd`;
+  }
+
+  return `${num}th`;
+}

practice-tdd/get-ordinal-number.test.js

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+import { getOrdinalNumber } from "./get-ordinal-number.js";
+// In this week's prep, we started implementing getOrdinalNumber.
+
+// Continue testing and implementing getOrdinalNumber for additional cases.
+// Write your tests using Jest — remember to run your tests often for continual feedback.
+
+// To ensure thorough testing, we need broad scenarios that cover all possible cases.
+// Listing individual values, however, can quickly lead to an unmanageable number of test cases.
+// Instead of writing tests for individual numbers, consider grouping all possible input values
+// into meaningful categories. Then, select representative samples from each category to test.
+// This approach improves coverage and makes our tests easier to maintain.
+
+// Case 1: Numbers ending with 1 (but not 11)
+// When the number ends with 1, except those ending with 11,
+// Then the function should return a string by appending "st" to the number.
+test("should append 'st' for numbers ending with 1, except those ending with 11", () => {
+  expect(getOrdinalNumber(1)).toEqual("1st");
+  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 11, 12 or 13", () => {
+  expect(getOrdinalNumber(11)).toEqual("11th");
+  expect(getOrdinalNumber(12)).toEqual("12th");
+  expect(getOrdinalNumber(13)).toEqual("13th");
+  expect(getOrdinalNumber(111)).toEqual("111th");
+});
+
+test("should append 'th' for all other numbers", () => {
+  expect(getOrdinalNumber(4)).toEqual("4th");
+  expect(getOrdinalNumber(10)).toEqual("10th");
+  expect(getOrdinalNumber(100)).toEqual("100th");
+});