Unable to import mocha API functions from 'mocha'

Prerequisites

• Checked that your issue hasn’t already been filed by cross-referencing issues with the faq label
• Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn’t just a feature that actually isn’t supported in the environment in question or a bug in your code.
• ‘Smoke tested’ the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
• Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with: node node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend that you not install Mocha globally.

Description

It is no longer possible to do ES6 style imports from mocha. e.g.

import { beforeEach, afterEach } from 'mocha';

import { describe, it } from 'mocha';

Steps to Reproduce

Write a my-test.js module like

import { describe, it } from 'mocha';

describe('A test', function () {
  it('should thing', function () {
  });
});

Expected behavior:

This test runs and passes

Actual behavior:

Something like

TypeError: (0 , mocha__WEBPACK_IMPORTED_MODULE_2__.describe) is not a function

(In this case webpack is the bundler)

Reproduces how often:

100%

Versions

I believe this was introduced by this PR: https://github.com/mochajs/mocha/pull/4746 and released as version 9.1.2

Additional info

I agree with the general goal in the PR: to stop polluting the mocha module with the contents of global; but it throws the baby out with the bathwater because this was previously how you could write self-documenting import statements which keeps linters happy. eslint:recommended contains no-undef so if you are writing your tests in modules and bundling them together, you are now in a pickle.

[juergba]

@apellerano-pw @PaperStrike thank you, guys.

In Node this currentContext is set to global (which corresponds to globalThis / window / ?? after bundling). We use a proxy for setting currentContext since in parallel mode each process has its own global. In browser there is no parallel mode, so evtl. by just adding var currentContext = global; to browser-entry.js should do the trick.

I tend to the second solution. It partially does what we had before, assigning from global to mocha, this time just more selective.

Some months ago we bundled to IIFE format, then had to switched to UMD due to problems with other bundlers using our bundle. Mocha, mocha , and global are not identical in these two formats. So - when we drop IE11 with next major release - I’m dreaming of bundling to the ESM format. Which hopefully should be easier to understand and also capable for other bundlers.

[apellerano-pw]

Thank you for suggesting a patch, @juergba. I tested the following patch and it works.

[
  'after',
  'afterEach',
  'before',
  'beforeEach',
  'context',
  'describe',
  'it',
  'specify',
  'xcontext',
  'xdescribe',
  'xit',
  'xspecify'
].forEach(function (key) {
  mocha[key] = global[key];
});

I added the context and specify (and xcontext, xspecify) entries to the array since they are synonyms for describe and it respectively.