JavaScript JavaScript Unit Testing Improving Our Tests Catching an Error

Alejandro Molina
Alejandro Molina
3,997 Points

Stuck on code challenge

I am stuck on this code challenge and am sure I am doing something wrong. Can someone guide me on what I should be doing correctly?

Here is the code so far:

subtraction_spec.js
var expect = require('chai').expect

describe('subtraction', function () {
  var subtraction = require('../WHEREVER')  
  it('only works with numbers', function () {
    var number1;
    var number2;
    var handler = function () {typeof number1 !== 'number' || typeof number2 !== 'number' };
    expect(handler).to.throw(Error);
    expect(handler).to.throw('subtraction only works with numbers!');
  })
})
subtraction.js
function subtraction (number1, number2) {
  if (typeof number1 !== 'number' || typeof number2 !== 'number') {
    throw Error('subtraction only works with numbers!')
  }
  return number1 - number2
}

1 Answer

Steven Parker
Steven Parker
207,988 Points

It looks like you were duplicating the subtract function a bit in your test function handler. All you really need to do is to call the subtract function there, and be sure to give it at least one invalid argument.

It might look something like this:

    var handler = function () { subtraction(21, 'junk') };