AVA tests are broken after v0.19.2 for default exports

[Lichtjaeger]

In addition to #233.

If I use the import statement for default exports with mjs files (import <packagename> from '<filename>.mjs') it results in an object with a "default" property.

This "default" property contains the real default export. This is also true for imports like import { default as <packagename> } from '<filename>.mjs'.

Here a ZIP file with a small test project.

Named exports do work.

[jdalton]

Hi @Lichtjaeger!

Thanks for the repro!

ava uses Babel to process test files so you'll want to use the @std/esm option of

"@std/esm": "cjs"

or long form

"@std/esm" {
  "cjs": true,
  "esm": "js"
}

Then your tests will work properly.

Update:

I added the ava options tip to readme.
When ava adds their how-to, I'll link to that.

[Lichtjaeger]

Is it possible to limit this behavior only to AVA?

I would like to use esm in my source files the most native way. For example, if I use the "cjs" option it will be possible to use __dirname and I'm not forced to use import.meta.url, so I can accidentally use __dirname. If I switch to native esm or copy my code into a project with native esm support this could result in an error.

[jdalton]

Is it possible to limit this behavior only to AVA?

It will be in the next release of AVA. They will make it so that when you use @std/esm it will bypass Babel and allow you to load without it. I'll also look into making sure .esmrc files in the test folder can be used.

[Lichtjaeger]

Thanks a lot. Sounds great.

[Lichtjaeger]

I can confirm: it works with the "cjs" option.

[jdalton]

Oh hey, you can also use the option:

"@std/esm": {
  "cjs": {
    "interop": true
  }
}

to just get the Babel CJS compat.

[Lichtjaeger]

Nice. Do you also know how to make this work with wallaby.js?

[jdalton]

I've asked at wallabyjs/public#1468.

[ArtemGovorov]

Added the @std/esm configuration notes to wallaby docs.

[jdalton]

Thank you @ArtemGovorov!