Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

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
216,165 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') };