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JavaScript

Posted by Kelsea Anderson
Kelsea Anderson
12,632 Points

JavaScript Unit Testing: A Testing Test

I'm working through JavaScript Unit Testing and am stuck on the challenge called A Testing Test. The question asks you to write a test spec that proves the clone function returns an object where all properties match with the code below. I have no idea where to begin with this. Any help would be appreciated!

var expect = require('chai').expect
describe('clone', function () {
    var clone = require('./clone.js')
    it('some description string', function () {
        // YOUR CODE HERE
    })
})

And here is the function

function clone (objectForCloning) {
    return Object.assign({}, objectForCloning)
}
module.exports = clone

1 Answer

Josh Cummings
Josh Cummings
16,310 Points

Hi Kelsea,

Given the following function:

function clone(objectForCloning) {
    return Object.assign({}, objectForCloning);
}
module.exports = clone;

We can see that it should return an object that is a clone of the object you pass in as a parameter. Looking at the Chai documentation, can you find a method that would help us test if the object you pass in has the same key and value as our output?

=========SPOILER=========

The property method is one we can use.

// .property(name, [value])
var obj = { foo: 'bar' };
expect(obj).to.have.property('foo', 'bar');

Then we can test like this:

var expect = require('chai').expect
describe('clone', function () {
    var clone = require('./clone.js');
    it('should return an object where all properties match', function () {
        expect(clone({a: 1})).to.have.property('a', 1);
    });
});

Resources:

Chai Docs

MDN - Assign

Kelsea Anderson
Kelsea Anderson
12,632 Points

Thank you so much!!

William Forbes
William Forbes
21,469 Points

I know this is bringing back a dead thread but I have tried

expect(JSONOBJECT).to.deep.equal(clone(JSONOBJECT));

and this fails the challenge. IS there a reason for this does this not test if they are the same object?