jest.mock is not hoisted if jest is imported from @jest/globals

[valeneiko]

Describe the bug

If I configure jest to not inject globals (injectGlobals: false) and instead import it explicitly: import { describe, expect, it, jest } from '@jest/globals';

Calls to jest.mock(...) are no longer hoisted to the top of the file.

Input code

import { setTimeout } from 'timers/promises';

import { describe, expect, it, jest } from '@jest/globals';

jest.mock('timers/promises', () => ({
  setTimeout: jest.fn(() => Promise.resolve())
}));

describe('suite', () => {
  it('my-test', () => {
    const totalDelay = jest
          .mocked(setTimeout)
          .mock.calls.reduce((agg, call) => agg + (call[0] as number), 0);
    expect(totalDelay).toStrictEqual(0);
  })
})

Config

{
  "$schema": "https://json.schemastore.org/swcrc",
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true,
      "dynamicImport": true
    },
    "transform": {
      "react": {
        "runtime": "automatic"
      }
    },
    "baseUrl": "./",
    "target": "es2021",
    "keepClassNames": true
  },
  "sourceMaps": "inline",
  "inlineSourcesContent": true,
  "isModule": true,
  "module": {
    "type": "commonjs",
    "ignoreDynamic": false
  }
}

Playground link

https://play.swc.rs/?version=1.3.10&code=H4sIAAAAAAAAA2WQT0%2FDMAzF7%2FkUvtURpdsZNMQB7pPghjikqVcFkqZLXMQ09buTpBrlT6Qcnp%2F9%2FEuMG31gOEMkfjaO%2FMQwwyF4BxUnHeJmTMJEitWtEObS3lHUwbRUA32OpLkGk%2B4bxXX8PqtNb32rbBnOunFev%2BO%2F6BpQwu4O8CzgB8pNSWwOAy72fulvAkVvPwilFLOUKfqCg1WcDNN3Xo4zjJU7XXNK%2BlUH0H5IvOxZ2Qey6gS7sq94yym41OGKJP%2B6jVbWxoTUTZoQVd%2FXkEtlT1JwBZj1y%2FYVVIRhci0FWcM2ceeQ5f9wpZAN%2BycORvPjcVIWl8Y5P1V8AS8JMp6vAQAA&config=H4sIAAAAAAAAAz2QMW7DMAxF70J0DOw2o9d06ZAuRQ7AKowj16IEkkJrGL57abvp9vn4%2BSVyhicNd0oIHdzNinZtO2jmZqdqWajJ0rf6HSTAAQYN0M1QUJRkVTqx4Y%2BP21RIg8RibjN1ZFLpANeJMcXwlkoW2%2BHiBkHWW5a0ZghhsE1UtpjI07BaTmgxwOLuT1S6yOi8add0lJ58AEiPz8cXJ19E5TSi6jsm0v9XNFcJdMbiCCKPkcnNu%2FjYenrKbMT2%2BG3Uc77WkR51%2BqvmbT9PCTmlzIOuOT37eV73%2FaC74ai0LL%2BwXm0pUwEAAA%3D%3D

Expected behavior

Compiled output to match ts-jest:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const globals_1 = require("@jest/globals");
jest.mock('timers/promises', () => ({
    setTimeout: jest.fn(() => Promise.resolve())
}));
const promises_1 = require("timers/promises");
...

jest.mock(...) call should be hoisted to the top of the file together with its import statement.

Actual behavior

The code is compiled as is, and jest.mock(...) calls are not hoisted. This prevents mocks from working, since the non-mocked module is imported before jest had a chance to mock it.

"use strict";
Object.defineProperty(exports, "__esModule", {
    value: true
});
const _promises = require("timers/promises");
const _globals = require("@jest/globals");
_globals.jest.mock('timers/promises', ()=>({
        setTimeout: _globals.jest.fn(()=>Promise.resolve())
    }));

Version

1.3.10

Additional context

When there are no imports from @jest/globals, compiled output from swc is correct -jest.mock(...) calls are hoisted to the top of the file.

[kdy1]

Imports are hoisted because you used ESM syntax

[valeneiko]

@kdy1 Can you explain in a bit more detail? I am not sure I understand what you meant.

The input file is a typescript file. I am expecting it to be compiled to CJS.

I was expecting jest.mock(...) to be compiled the same in both of these cases:

• import {jest} from "@jest/globals"
• using global jest object

[kdy1]

swc-project/swc#5205

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.

[magic-akari]

This matter may be beyond the scope of the ESM specification. ESM is the standard we adhere to.
However, it should be noted that the Babel plugin will hoist Jest-related methods.
https://github.com/jestjs/jest/blob/b7ae0b85e981eae0e373d98ab2ae8fe497d90027/packages/babel-plugin-jest-hoist/src/index.ts#L31-L37

Additionally, our plugin has also done similar things, but it does not cover everything.

plugins/packages/jest/src/lib.rs

Line 60 in 7aca008

Expr::Ident(i) if i.sym == *"jest" => match prop {

So this should be a technically feasible solution. We can fix this issue in the swc jest plugin.

[magic-akari]

The core issue lies here: In Babel, the passes are structured like an onion model, allowing plugins to define both pre and post phases.
https://github.com/jestjs/jest/blob/b7ae0b85e981eae0e373d98ab2ae8fe497d90027/packages/babel-plugin-jest-hoist/src/index.ts#L405-L409

In SWC, passes follows the pipeline model, and re-entering a plugin after the import phase (CommonJS) is a challenge.