Chai - Testing for values in array of objects

Question

I am setting up my tests for the results to a REST endpoint that returns me an array of Mongo database objects.

[{_id: 5, title: 'Blah', owner: 'Ted', description: 'something'...},
 {_id: 70, title: 'GGG', owner: 'Ted', description: 'something'...}...]

What I want my tests to verify is that in the return array it conatins the specific titles that should return. Nothing I do using Chai/Chai-Things seems to work. Things like res.body.savedResults.should.include.something.that.equals({title: 'Blah'}) error out I'm assuming since the record object contains other keys and values besides just title.

Is there a way to make it do what I want? I just need to verify that the titles are in the array and don't care what the other data might be (IE _id).

Thanks

David Starkey · Accepted Answer · 2019-04-18 15:09:26Z

44

This is what I usually do within the test:

var result = query_result;

var members = [];
result.forEach(function(e){
    members.push(e.title);
});

expect(members).to.have.members(['expected_title_1','expected_title_2']);

If you know the order of the return array you could also do this:

expect(result).to.have.deep.property('[0].title', 'expected_title_1');
expect(result).to.have.deep.property('[1].title', 'expected_title_2');

edited Apr 18, 2019 at 15:09

David Starkey

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answered Jan 18, 2017 at 18:01

user2263572

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2 Comments

Jared Yach Over a year ago

Thank you. since I cannot guarantee the result order, that works to solve what I want to test for

oruckdeschel Over a year ago

I would like to mention, that while your answer is correct, it might be better to use .map() instead of .forEach() in combination with push(). Map is faster than forEach [1] and more readable. :) [1] codeburst.io/javascript-map-vs-foreach-f38111822c0f

Kev · Accepted Answer · 2017-07-28 18:26:58Z

38

As stated here following code works now with [email protected] and chai-things. I just love the natural readability of this approach.

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

chai.use(require('chai-like'));
chai.use(require('chai-things')); // Don't swap these two

expect(data).to.be.an('array').that.contains.something.like({title: 'Blah'});

edited Jul 28, 2017 at 18:26

Kev

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answered Jul 14, 2017 at 10:10

kub1x

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Comments

Guido Dizioli · Accepted Answer · 2020-05-15 14:30:40Z

12

Probably the best way now a days would be to use deep.members property

This checks for unordered complete equality. (for incomplete equality change members for includes)

i.e.

expect([ {a:1} ]).to.have.deep.members([ {a:1} ]); // passes
expect([ {a:1} ]).to.have.members([ {a:1} ]); // fails

Here is a great article on testing arrays and objects https://medium.com/building-ibotta/testing-arrays-and-objects-with-chai-js-4b372310fe6d

DISCLAIMER: this is to not only test the title property, but rather a whole array of objects

answered May 15, 2020 at 14:30

Guido Dizioli

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Comments

Sebastien Horin · Accepted Answer · 2020-05-17 04:16:41Z

10

ES6+

Clean, functional and without dependencies, simply use a map to filter the key you want to check

something like:

const data = [{_id: 5, title: 'Blah', owner: 'Ted', description: 'something'},{_id: 70, title: 'GGG', owner: 'Ted', description: 'something'}];


expect(data.map(e=>({title:e.title}))).to.include({title:"Blah"});

or even shorter if you only check one key:

expect(data.map(e=>(e.title))).to.include("Blah");

https://www.chaijs.com/api/bdd/

answered May 17, 2020 at 4:16

Sebastien Horin

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Comments

kli · Accepted Answer · 2021-11-28 14:22:49Z

1

I loved the suggestion from @sebastien-horin But another way with Should syntax (for the specific property):

const data = [
    { _id: 5, title: 'Blah', owner: 'Ted', description: 'something' },
    { _id: 7, title: 'Test', owner: 'Ted', description: 'something' },
];

data.map((e) => e.title).every((title) => title.should.equal('Blah'));

answered Nov 28, 2021 at 14:22

kli

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Comments

KyleMit · Accepted Answer · 2021-10-13 18:02:40Z

0

Here is another approach that I found to be more helpful. Basically, use string interpolation and map your array of objects to an array of string literals. Then you can write expectations against the array of strings.

const locations: GeoPoint[] = [
  {
    latitude: 10,
    longitude: 10
  },
  {
    latitude: 9,
    longitude: 9
  },
  {
    latitude: -10,
    longitude: -10
  },
  {
    latitude: -9,
    longitude: -9
  }
];
const stringLocations: string[] = locations.map((val: GeoPoint) => 
  `${val.latitude},${val.longitude}`
);

expect(stringLocations).to.contain('-9.5,-9.5');
expect(stringLocations).to.contain('9.5,9.5');

edited Oct 13, 2021 at 18:02

KyleMit♦

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answered Dec 2, 2019 at 9:15

Cazr

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Comments

adel parsa · Accepted Answer · 2023-06-01 09:10:42Z

0

I had the same problem and fixed it by the below assertion:

res.body.savedResults[0].title.should.eql("you value");
// or
expect(res.body.savedResults[0].title).to.be.eql("your value")

Actually, I use assertions directly on value. it doesn't matter what it is.

answered Jun 1, 2023 at 9:10

adel parsa

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Comments

p.desterlich · Accepted Answer · 2017-04-24 08:25:15Z

An alternative solution could be extending the array object with a function to test if an object exists inside the array with the desired property matching the expected value, like this

/**
 * @return {boolean}
 */
Array.prototype.HasObjectWithPropertyValue = function (key, value) {
    for (var i = 0; i < this.length; i++) {
        if (this[i][key] === value) return true;
    }
    return false;
};

(i put this in my main test.js file, so that all other nested tests can use the function)

Then you can use it in your tests like this

var result = query_result;
// in my case (using superagent request) here goes
// var result = res.body;

result.HasObjectWithPropertyValue('property', someValue).should.equal(true);

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