Require JSON as deep copy

Question

I am writing tests right now for my node application. I have fixtures which I use to test my data and I ran into the Problem, that when I alter any of them in a method, then they are globally altered for all the other tests as well, which obviously has to do with referencing. Now I figured if I write my fixtures into a JSON and require that JSON in each file then they will have unique references for each file, which turns out now, they don't. My question would be: is there an easy way to handle fixtures in Node such that every file has an instance of the fixtures which won't affect the other test files.

The way I currently import my fixtures in every test file:

const {fixture1, someOtherFixture } = require('../../../../../fixtures/keywords.json');

Answer 1

require calls are cached, so once you call it, consecutive calls will return the same object.

You can do the following:

const {fixture1, someOtherFixture } = require('../../../../../fixtures/keywords.json');

const fixtureCopy = JSON.parse(JSON.stringify(fixture1));
const someOtherFixtureCopy = JSON.parse(JSON.stringify(someOtherFixtureCopy));

or use a package:

• deepcopy
• clone

const deepcopy = require('deepcopy');
const {fixture1, someOtherFixture } = require('../../../../../fixtures/keywords.json');

const fixtureCopy = deepcopy(fixture1);
const someOtherFixtureCopy = deepcopy(someOtherFixtureCopy);

Or change your module to export a function that will return new copies everytime. This is the recommended approach in my opinion.

module.exports = {
   get() {
      return deepcopy(fixture); // fixture being the Object you have 
   }
}

const fixture = require('./fixture');

const fixture1 = fixture.get();