Pushing object into globally declared array in Node.js

I never used global variables in Node.js so I have trouble understanding why this wont work. I am declaring global variable that is array, than I want to push some object into it and for sake of debugging I just want to stringify it. I tried it like this:

var test = require('./api/test'); //my class
global.arrayOfObjects = []; //declaring array
global.arrayOfObjects.push = new test(123); //docs3._id is something I return from db
console.log(JSON.stringify(global.arrayOfObjects)); //I get []

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