add card-validator code and tests

Author: tomdu3

Sprint-3/4-stretch/card-validator.js

@@ -0,0 +1,38 @@
+function validateCreditCardNumber(cardNumber) {
+  // Check if the card number is a positive integer.
+  if (typeof cardNumber !== "number" || cardNumber < 0) {
+    return false;
+  }
+
+  const cardNumberString = String(cardNumber);
+  // Check if the card number has at least two different digits
+  const uniqueDigits = new Set(cardNumberString);
+
+  if (uniqueDigits.size < 2) {
+    return false;
+  }
+
+  // Check if the card number has exactly 16 digits.
+  if (cardNumberString.length !== 16) {
+    return false;
+  }
+
+  // Check if the last digit is even
+  if (Number(cardNumberString.slice(-1)) % 2 !== 0) {
+    return false;
+  }
+
+  // Check if the sum of all the digits is greater than 16
+  const sumOfAllDigits = Array.from(cardNumberString).reduce(
+    (sum, digit) => sum + Number(digit),
+    0
+  );
+
+  if (sumOfAllDigits <= 16) {
+    return false;
+  }
+
+  return true;
+}
+
+module.exports = validateCreditCardNumber;

Sprint-3/4-stretch/card-validator.test.js

@@ -0,0 +1,91 @@
+const validateCreditCardNumber = require("./card-validator");
+
+test("Number must be 16 digits, all of them must be numbers.", () => {
+  // Arrange
+  const cardNumber = 1234567890123456;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(true);
+});
+
+test("Credit card number must have at least two different digits.", () => {
+  // Arrange
+  const cardNumber = 6262826262628262;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(true);
+});
+
+test("Credit card with only one repeating digit is invalid.", () => {
+  // Arrange
+  const cardNumber = 8888888888888888;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number cannot have an odd last digit.", () => {
+  // Arrange
+  const cardNumber = 1234567890123457;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number sum of all digits cannot be less than or equal to 16.", () => {
+  // Arrange
+  const cardNumber = 1000000000000000;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number sum of all digits must be greater than 16.", () => {
+  // Arrange
+  const cardNumber = 1234567890123452;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(true);
+});
+
+test("Credit card number must not be negative.", () => {
+  // Arrange
+  const cardNumber = -1234567890123456;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number must be a number.", () => {
+  // Arrange
+  const cardNumber = "1234567890123456";
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number must have exactly 16 digits.", () => {
+  // Arrange
+  const cardNumber = 212222222212222;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});
+
+test("Credit card number cannot have less or more than 16 digits.", () => {
+  // Arrange
+  const cardNumber = 212222222212222;
+  // Act
+  const result = validateCreditCardNumber(cardNumber);
+  // Assert
+  expect(result).toEqual(false);
+});