How do I partially compare deeply nested objects in Cypress assertions?

Question

I'm using Cypress as my automation framework for both API and UI tests. I've written multiple API tests that are running and passing but they're only validating that the response.status returns a 200. I want to compare the response json from a GET against a stored "expected" response to confirm that the JSON response data is correct.

I've tried different variations of to.deep.equal and deepEquals in my .then(response => {} code block. But I don't want to validate that just one field is returning the correct value, I want to validate whether a bunch of different fields are returning the correct values. My GET request returns over 100 lines of nested JSON fields/values and I only want to validate 20 or so fields/values nested inside each other.

cy.request({
    method: 'GET',
    log: true,
    url: 'https://dev.api.random.com/calculators/run-calculate/524/ABC',

    headers: {
        'content-type': 'application/json',
        'x-api-key': calcXApiKey
    },
    body: {}
}).then(response => {
    const respGet = response.body
    const tPrice = response.body.data.calculations.t_costs[0].comparison.t_price
    cy.log(respGet, tPrice)
    assert.deepEqual({
        tPrice
    }, {
        t_price: '359701'
    })
       // assert.equal(response.status, 200) -- This works great
})

Error= expected { tPrice: undefined } to deeply equal { t_price: 359701 }

For any future searchers, there's a thing called deepInclude besides deepEqual — Loi Nguyen Huynh
– Loi Nguyen Huynh, Commented Mar 22, 2022 at 16:30

dwelle · Accepted Answer · 2019-08-29 12:20:27Z

4

In your example, you're comparing object { tPrice: tPrice } with { t_price: '359701' }, that's why it's always going to fail because the keys are different (apart from the fact that the tPrice variable value is undefined).

If you're already storing the actual value in a variable, there's no need to make an object out of it and use deepEqual. You can do:

const tPrice = response.body.data.calculations.t_costs[0].comparison.t_price
assert.equal(tPrice, '359701');

As to your other question, if I understand it correctly, your response looks like:

{
  data: {
    calculations: {
      t_costs: [
        { comparison: { t_price: "1111" } },
        { comparison: { t_price: "2222" } },
        { comparison: { t_price: "3333" } },
        { comparison: { t_price: "4444" } },
        /* ... */
      ]
    }
  }
}

And you want to assert just a few of those t_costs objects.

For that it's best to use a chai plugin such as debitoor/chai-subset.

To set it up:

npm install --save-dev chai-subset

In your cypress/support/index.js:

const chai = require('chai');
const chaiSubset = require('chai-subset');
chai.use(chaiSubset);

In your spec:

/* ... */
expect( response.body.data.calculations.t_costs )
    .to.containSubset([
        { comparison: { t_price: "1111" } },
        { comparison: { t_price: "3333" } }
    ]);

answered Aug 29, 2019 at 12:20

dwelle

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2 Comments

Chase Small Over a year ago

This worked great. Thank you so much for your help. It's so much simpler than I was making it haha.

Max Liashuk Over a year ago

Keep in mind, chai-subset works but error reporting is terrible. You need to manually analyze why it's failing. There is no explicit error of where field doesn't match.

Idleness · Accepted Answer · 2022-06-28 15:01:37Z

2

I was working on a very similar problem recently. I often forget that Cypress comes bundled with some decent packages; in this case Lodash which is good at dealing with arrays and objects such as a deeply nested JSON API return. I also had an expected return JSON that I wanted to compare to the full response JSON. After a bit of trial and error I did this:

expect(Cypress._.isMatch(response.body, expectedReturn)).to.be.true;

answered Jun 28, 2022 at 15:01

Idleness

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