Prototype should is not added when code run in a new context

When running the code in a new context, should is not added to the prototype. This code fail with “Cannot read property ‘be’ of undefined”

const vm = require("vm");

const code = "const chai = require(\"chai\");\n" +
	"chai.should();\n" +
	"const test = \"test\";\n" +
	"test.should.be.equal(\"test\");\n";
vm.runInNewContext(code, { global, require }, { filename: "test.js"});

A reproduction is available in this repository

[meeber]

Disclaimer: I’m not an expert on Node’s VM module.

I don’t think what you’re doing is going to work. Consider this example without Chai:

const vm = require("vm");

Object.prototype.meow = 42;
global.Object.prototype.purr = 43;

console.log('Outer', {}.meow, {}.purr);

const code = "console.log('Inner', {}.meow, {}.purr)\n";
vm.runInNewContext(code, { console, global, require }, { filename: "test.js"});

The output is:

Outer 42 43 Inner undefined undefined

Even if you move Object.prototype.meow = 42; global.Object.prototype.purr = 43; into a separate file, and then require that file from within the sandbox, the inner console.log will still display “Inner undefined undefined”.

In terms of Chai: Essentially what’s happening is that calls to Object.prototype inside of Chai’s code are referencing the outer Object not the inner Object. I believe this is due to how require works when passed into the sandbox environment.

[keithamus]

Hey @CodeTroopers thanks for the issue.

We’ve added this to our Roadmap https://github.com/chaijs/chai/projects/2! We’ll be releasing chai 5 soon, but for now I’ll close this issue because it is tracked on our roadmap.