Luhn formula multi-step testing example

lazy-dev2-example3.js

describe('Luhn Formula Example', function () {

  // Final test at the top

  it('should validate IDs according to the Luhn formula', function () {
    expect(validateID('120488395')).to.be.ok();
  });

  // 1. Convert a string of numbers to an integer

  it('should check that number characters can be read as digits', function () {
    function charConversion (char) {
      var result;

      result = parseInt(char, 10);

      return result;
    }

    expect(charConversion('8')).to.be(8);
  });

  // 2. Take the parsed number and double every digit
  // 3. Add up individual digits if doubled >= 10

  it('should check that doubled numbers greater than 10 are broken down to single digits', function () {
    function digitCheck (num) {
      var sum,
          doubled;

      doubled = num * 2;

      if (doubled >= 10) {
        sum = 1 + doubled % 10;
      } else {
        sum = doubled;
      }

      return sum;
    }

    expect(digitCheck(8)).to.be(7);
  });


});