It doesn't appear that there's any way to customize swc</cod

This is now actually a major blocker for using ESM in jest (<a class="issue-link js-is

Much appreciated! Thank you. 💖 <a target="_blank" rel="noopener nor

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No way to override jsc or module swc configuration? about jest HOT 5 CLOSED

swc-project commented on June 9, 2024 2

No way to override jsc or module swc configuration?

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Comments (5)

kdy1 commented on June 9, 2024 1

I'll take a look soon.

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kdy1 commented on June 9, 2024 1

Fixed with the new version of @swc/jest.
You can use v0.2.0 to do this.

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buschtoens commented on June 9, 2024

This is now actually a major blocker for using ESM in jest (jestjs/jest#9430).

When I comment out the line that forces commonjs:

jest/index.ts

Line 48 in 9d81a9a

set(swcOptions, 'module.type', 'commonjs')

And use these configs:

// jest.config.js
/** @type {import('@jest/types').Config.InitialOptions} */
module.exports = {
  // testEnvironment: 'jsdom', // Irrelevant for the bug. Enable at will.
  transform: {
    '^.+\\.tsx?$': '@swc/jest'
  },
  extensionsToTreatAsEsm: ['.ts']
};

// .swcrc
{
  "sourceMaps": true,
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true, // Might as well be false, if not transpiling `.tsx`.
      "decorators": false,
      "dynamicImport": true // Required.
    },
    "target": "es2020",
    "loose": true
  }
}

ESM and jest work just fine, with the limitations noted in the tracking issue: jestjs/jest#9430

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buschtoens commented on June 9, 2024

Much appreciated! Thank you. 💖

What do you think a good long-term plan would be for the config patching? AFAICT, these options are crucial when wanting to use TypeScript & ESM with jest:

{
  "sourceMaps": true,         // Important
  "jsc": {
    "parser": {
      "syntax": "typescript", // Important
      "tsx": true,            // Depending on whether `.tsx` is targeted as well.
      // "decorators": false,
      "dynamicImport": true   // Important.
    },
    "target": "es2020"        // I think that was important for dynamic import stuff.
  },
  "module": null              // Important
}

{
  transform: {
    '^.+\\.tsx?$': '@swc/jest'
  },
  extensionsToTreatAsEsm: ['.ts', '.tsx']
}

It would be nice, if these options could eventually be applied correctly out-of-the-box.

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kdy1 commented on June 9, 2024

{
  "sourceMaps": true,         // Maybe this should be true by default.
  "jsc": {
    "parser": {
      "syntax": "typescript", // Should be specified, because jest can be used with non-ts codes.
      "tsx": true,            // Making this true will just work, if it's accepted by tsc
      // "decorators": false,
      "dynamicImport": true   // If this is required by jest? If so, it should be default
    },
    "target": "es2020"        // Not important for dynamic imports.
  },
  "module": null              // This is null by default
}