How to assert the values in a downloaded file using Cypress - automation

Question

I am downloading a zip file which has a json zipped. Using cy.readfile, I am able to read the content but I am not sure what commands can be used to assert on the values inside.
(Please let me know if there is a way to unzip the file before reading)
I need to verify I have 3 objectids present in the json and also some values of the elements.
I tried the below approach, but it did not work.
cy.readFile(`/Users/${username}/Downloads/${fileName}.zip`)
.should('contain','objectid').and('have.length',3);
The above command did not work for me :(
Could someone help me with some examples? I am new to cypress and coding,therefore struggling a little.

Answer 1

You can change the download folder in every test case!!
Look into your index.js in -> cypress -> plugins -> index.js and write this :
module.exports = (on, config) => {
on('before:browser:launch', (browser, options) => {
const downloadDirectory = 'C:\\downloads\\'; // this is the path you want to download
options.preferences.default['download'] = { default_directory: downloadDirectory };
return options;
});
};

Answer 2

Do it like this
cy.readFile(`/Users/${username}/Downloads/${fileName}.zip`)
.then((data) => {
// you can write whatever assertions you want on data
debugger;
console.log(data);
expect(data).to....
})
You can put debugger as above and logs to check what data contains and then assert
Use this link to know about available assertions https://docs.cypress.io/guides/references/assertions.html#BDD-Assertions

Answer 3

So here is the approach I am following.It is quite lengthy, but still posting as it might be helpful for someone.Please comment if you have any suggestions for improvements here.
I am using npm-unzipper to unzip the downloaded file.
Step 1: $ npm install unzipper
Step 2:In plugins > index.js
const fs = require('fs');
const os = require('os');
const osplatform = os.platform();
const unzipper = require('unzipper');
const userName = os.userInfo().username;
let downloadPath =`/${userName}/Downloads/`;
if (osplatform == 'win32'){
downloadPath = `/Users/${userName}/Downloads/`;
}
on('task', {
extractzip(zipname) {
const zipPath = downloadPath + zipname;
if (fs.existsSync(zipPath)) {
const readStream = fs.createReadStream(zipPath);
readStream.pipe(unzipper.Extract({path: `${downloadPath}`}));
const jsonname = 'testfile.json'
const jsonPath = downloadPath + jsonname;
return jsonPath;
}
else{
console.error('file not downloaded')
return null;
}
}
})
Step 3:support > commands.js
Cypress.Commands.add('comparefiles', { prevSubject: false }, (subject, options = {}) => {
cy.task('extractzip', 'exportfile.zip').then((jsonPath) => {
cy.fixture('export.json').then((comparefile) => {
cy.readFile(jsonPath).then((exportedfile) => {
var exported_objectinfo = exportedfile.objectInfo;
var compare_objectinfo = comparefile.objectInfo;
var exported_metaInfo = exportedfile.metaInfo;
var compare_metaInfo = comparefile.metaInfo;
expect(exported_objectinfo).to.contain.something.like(compare_objectinfo)
expect(exported_metaInfo).to.have.deep.members(compare_metaInfo)
})
})
});
});
Step 4: specs > exportandcompare.js
cy.get('[data-ci-button="Export"]').click();
cy.comparefiles();