Migrate to ESM

[kytta]

• [x] Install Vitest
• [ ] Migrate sub-packages
  • [x] dual-publish
  • [ ] esbuild
  • [ ] figure out why sizes differ way too much (231 405 bytes)
  • [x] esbuild-why
  • [x] file
  • [x] preset-app
  • [x] preset-big-lib
  • [x] preset-small-lib
  • [x] size-limit
  • [ ] third party plugin used for testing uses imports incorrectly (without an extension)
  • [x] time
  • we could've used estimo v3 with ESM, but it's not available (https://github.com/mbalabash/estimo/issues/43)
  • test/get-running-time.test.js > calculates running time doesn't run on my machine, both Jest and Vitest
  • [x] webpack
  • [ ] webpack-css
  • [ ] figure out why it doesn't seem to bundle CSS at all (1450 70 bytes)
  • [x] webpack-why
• [x] update ESLint config
• [ ] test JS config with ESM

[kytta]

Things I'm stuck on at the moment (just to keep records):

1. Rewriting require into import doesn't work for something more complicated, like ESBuild and webpack plugins. I haven't figured out the whole errors yet.
2. When the plugins do work, they tend to provide different size results. For example, files compressed with ESBuild tend to be bigger than before, but I haven't figured out why yet. I've tried converting test files into both ESM and CJS, but none worked as expected. As such, snapshot tests fail

Also:

• Vitest doesn't have a plausible alternative to jest.setTimeout(15000); we have to set a timeout for every it() call or for every test per run via a config file, but not per test file. Instead of plastering it on every test, I only apply it to the ones that actually need more time

[ai]

Vitest doesn't have a plausible alternative to jest.setTimeout(15000); we have to set a timeout for every it() call or for every test per run via a config file, but not per test file. Instead of plastering it on every test, I only apply it to the ones that actually need more time

Try to remove it. Maybe we don’t need it anymore (by increasing performance with new Node.js and esbuild).

Rewriting require into import doesn't work for something more complicated, like ESBuild and webpack plugins. I haven't figured out the whole errors yet.

Need some example to understand what exactly problems do you have

When the plugins do work, they tend to provide different size results. For example, files compressed with ESBuild tend to be bigger than before, but I haven't figured out why yet. I've tried converting test files into both ESM and CJS, but none worked as expected. As such, snapshot tests fail

If it is only a few bytes, it could happen just because of dependencies update (new esbuild compress a little different). Just updates tests and snapshots.

[kytta]

Alright, this is mostly done now, only couple of bugs left.

Rewriting require into import doesn't work for something more complicated, like ESBuild and webpack plugins. I haven't figured out the whole errors yet.

Need some example to understand what exactly problems do you have

Currently stuck on webpack-css with the following:

AssertionError: expected 70 to be greater than 1450
 ❯ packages/webpack-css/test/index.test.js:41:33
     39|   }
     40|   await run(config)
     41|   expect(config.checks[0].size).toBeGreaterThan(1450)
       |                                 ^
     42|   expect(config.checks[0].size).toBeLessThan(2400)
     43| })

Seems like the non-JS requires inside nonjs.js get completely ignored, as the file size stays the same. I wonder if it's because I still require() them instead of using dynamic imports — haven't had time to test this out yet.

When the plugins do work, they tend to provide different size results.

If it is only a few bytes, it could happen just because of dependencies update (new esbuild compress a little different). Just updates tests and snapshots.

For the "supports ignore" test on esbuild, it doesn't seem to, well, support ignore, as the bundle size is way bigger than expected

[ai]

AssertionError: expected 70 to be greater than 1450

70 bytes is nothing. Just update the size.

For the "supports ignore" test on esbuild, it doesn't seem to, well, support ignore, as the bundle size is way bigger than expected

This is more important bug. But with the current data I can’t give you any advice rather than keep debuging.

[kytta]

AssertionError: expected 70 to be greater than 1450

70 bytes is nothing. Just update the size.

How so? It is expected that the final webpack bundle is in the 1450–2400 range, but it's just 70 (which coincidentally matches the size of the unbundled file), so 2–3 orders of magnitude smaller.

[ai]

It is expected that the final webpack bundle is in the 1450–2400 range, but it's just 70

Got it! Yes, it is not expected (I thought that it is 70 less, not equal to 70).

[ai]

Closing for https://github.com/ai/size-limit/pull/338