Running `dev:prepare` in the root of a module behaves differently than preparing in the playground

[cernymatej]

@lewebsimple pointed out an edge case where, if a module checks for the existence of a certain file, running the dev:prepare script will fail when executed from the root of the module (via @nuxt/module-builder).

Reproduction
https://github.com/lewebsimple/nuxt-module-layers-repro

const rootDirs = getLayerDirectories().map(({ root }) => root)
let discoverMePath
for (const rootDir of rootDirs) {
  if (existsSync(`${rootDir}/discover-me.txt`)) {
    discoverMePath = `${rootDir}/discover-me.txt`
    logger.info(`Found discover-me.txt in layer: ${rootDir}`)
    break
  }
}
if (!discoverMePath) {
  throw new Error('Required file discover-me.txt not found in any layer directories.')
}

Steps to reproduce

1. run pnpm dev:prepare in the root of the project
2. see that it fails

Additional context

This happens because the module's setup function runs initially without taking the playground directory into account, and only afterward does it run separately for the playground.

"dev:prepare": "nuxt-module-build build --stub && nuxt-module-build prepare && nuxi prepare playground",

[cernymatej]

One solution would be to add the playground/ layer into the prepare command from @nuxt/module-builder:

module-builder/src/commands/prepare.ts

Lines 19 to 39 in 63ccc33

	return runCommand('prepare', [cwd], {
	overrides: {
	compatibilityDate: '2024-04-03',
	typescript: {
	builder: 'shared',
	},
	imports: {
	autoImport: false,
	},
	modules: [
	resolve(cwd, './src/module'),
	function (_options, nuxt) {
	nuxt.hooks.hook('app:templates', (app) => {
	for (const template of app.templates) {
	template.write = true
	}
	})
	},
	],
	} satisfies NuxtConfig,
	})

However, this would bring other problems... The worst one being that module playgrounds would require a resolved path to the module in nuxt.config.ts:

import { createResolver } from '@nuxt/kit'
const { resolve } = createResolver(import.meta.url)

export default defineNuxtConfig({
  modules: [
    resolve('../src/module')  // <---- instead of `'../src/module'`
  ],

[lewebsimple]

Any update on this?

[cernymatej]

@lewebsimple we can't introduce the breaking change at the moment and I don't really like the solution to be honest...

@danielroe do you have any ideas?

[BobbieGoede]

This is technically expected behavior, the nuxt-module-build prepare command needs to run the module setup in order to generate module types.

In my experience it's best to skip throwing errors when nuxt.options._prepare === true, that way the module setup can still register its plugins/components/etc resulting in accurate type generation regardless of dev/prod errors.

So in the case of the repro:

// allow during type generation (nuxt prepare)
if (!discoverMePath && !_nuxt.options._prepare) {
  throw new Error('Required file discover-me.txt not found in any layer directories.')
}