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JavaScript JavaScript Unit Testing Behavior Driven Development with Mocha & Chai A Testing Test!

Posted by Kathryn Notson
Kathryn Notson
25,941 Points

JavaScript Unit Testing > Behavior Driven Development with Mocha and Chai > A Testing Test!

This code doesn't work which is straight from the Chai assertion library. Clone.js doesn't work correctly, expected test to fail, but it passed.

clone_spec.js 
var expect = require('chai').expect;

describe('clone', function () {
    var clone = require('./clone.js');
    it('some description string', function () {

        expect({foo : 'bar'}).to.deep.equal({foo : 'bar'});

    })
})
clone.js 
function clone (objectForCloning) {
    return Object.assign({}, objectForCloning)
}

module.exports = clone

5 Answers

Kathryn Notson
Kathryn Notson
25,941 Points
Kathryn Notson
Kathryn Notson
25,941 Points

Timothy Schmidt:

Here's one example that I used: "Expect(clone).to.deep.equal({});" clone.js works correctly, specs don’t pass

Timothy Schmidt
Timothy Schmidt
4,806 Points
Timothy Schmidt
Timothy Schmidt
4,806 Points

Ok, I think I know where the misunderstanding is. clone isn't the object you're supposed to test, it's a function that is used to make the clone. You pass an object to the clone function and the result is what you need to test. So, using the example in your last comment, it would be:

expect( clone({}) ).to.deep.equal({});

But, it apparently doesn't work with empty objects, so you need to add a key to the object.

expect( clone({key: "value"}) ).to.deep.equal({key:"value"});

That line passed the exercise for me.

Timothy Schmidt
Timothy Schmidt
4,806 Points
Timothy Schmidt
Timothy Schmidt
4,806 Points

In the code you provided, you're not actually using the clone function. 

var expect = require('chai').expect;

describe('clone', function () {
    var clone = require('./clone.js');
    it('some description string', function () {
        // use clone function to clone an object.
        var objClone = clone({ foo : 'bar' });
        expect({foo : 'bar'}).to.deep.equal( objClone );

    })
})
Kathryn Notson
Kathryn Notson
25,941 Points
Kathryn Notson
Kathryn Notson
25,941 Points

Timothy Schmidt:

I don't understand what you said. The clone function in clone.js is exported & the code challenge question uses it.

Timothy Schmidt
Timothy Schmidt
4,806 Points
Timothy Schmidt
Timothy Schmidt
4,806 Points

The question doesn't use it on it's own. You're meant to use the clone function inside your unit test. So, inside your it function, you need to use clone and then use expect to test that the function provided the correct result.

Kathryn Notson
Kathryn Notson
25,941 Points
Kathryn Notson
Kathryn Notson
25,941 Points

Timothy Schmidt:

I've tried multiple iterations of "expect(clone).to.deep.equal(objectForCloning);", but nothing passes correctly so I can't complete this code challenge. I've read the Mozilla.org documentation on Object.assign() & also the Chai assertion library. Nothing has hit me to have an "Aha!" moment to realize what the correct answer is. My logic must be faulty.

Timothy Schmidt
Timothy Schmidt
4,806 Points
Timothy Schmidt
Timothy Schmidt
4,806 Points

That's strange. I went to the code challenge before posting to ensure my code worked before posting it. Have you tried using my solution?

If you could comment with one of your examples of using expect(clone).to.deep.equal(objectForCloning);, maybe I can see what's wrong.

Kathryn Notson
Kathryn Notson
25,941 Points
Kathryn Notson
Kathryn Notson
25,941 Points

Timothy Schmidt:

Thanks! That worked. I don't know what I was doing wrong unless I wasn't including enough () within the (clone()). This quiz question drove me nuts for the last 2 1/2 months! I was mulling over what I read in MDN & what the instructor said about ".deep.equal" in the video. I was going to review it all over again today, but you saved me the effort.