Jest does not allow constants called "global", not even in imported files.

[stimberm]

🐛 Bug Report

Jest fails tests with the following error as soon as some imported/required file defines a constant called "global".

SyntaxError: Identifier 'global' has already been declared

See https://github.com/stimberm/reproduce-jest-global-collision for an example.

Renaming the constant is a workaround, as is using var instead of const, but that is not feasible for dependencies. Specifically, the latest release of monaco-editor contains a constant called "global" and can therefore not be included in a jest test.

To Reproduce

Have a test require a file that defines a const global = ...;

Expected behavior

The test should run successfully.

Link to repl or repo (highly encouraged)

https://github.com/stimberm/reproduce-jest-global-collision

This stackoverflow question seems to be about the same issue.

envinfo

% npx envinfo --preset jest
npx: installed 1 in 1.366s

  System:
    OS: macOS 10.15.7
    CPU: (8) x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
  Binaries:
    Node: 12.18.3 - ~/.nvm/versions/node/v12.18.3/bin/node
    Yarn: 1.22.5 - ~/.nvm/versions/node/v12.18.3/bin/yarn
    npm: 6.14.8 - ~/.nvm/versions/node/v12.18.3/bin/npm
  npmPackages:
    jest: ^26.4.2 => 26.4.2

[jeysal]

Confirmed, but this will certainly not be an easy fix. jest-runtime injects this and extraGlobals as parameters in addition to normal Node module parameters, we'd need some way to set them as proper globals instead...

[github-actions]

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