Allow async config file exports

[TehShrike]

This would allow config files to be CommonJS files that pull in connection details from ESM files using dynamic imports.

Alternately, util.local could be changed to be async, and use dynamic imports if the file extension is .mjs or something, but forcing config files to be CJS while allowing asynchrony seemed less problematic.

[codecov-commenter]

Codecov Report

Merging #9 into master will decrease coverage by 2.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #9      +/-   ##
==========================================
- Coverage   48.07%   45.94%   -2.14%     
==========================================
  Files           2        2              
  Lines         104      111       +7     
==========================================
+ Hits           50       51       +1     
- Misses         54       60       +6     

Impacted Files	Coverage Δ
index.js	11.76% <0.00%> (+0.28%)	⬆️

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[lukeed]

I think I'm good with this. Just to make sure we're on the same page, can you share a demo config file that'd use this?

[lukeed]

Accident? 🤔

[TehShrike]

oh shit, yeah, apparently I accidentally wiped this out while going push-crazy on the command-line

[TehShrike]

Here's a config file I'm imagining:

module.exports = import('./environment.mjs').then(({ db_user, db_password }) => ({
	host: 'localhost',
	database: 'my_sweet_app',
	user: db_user,
	pass: db_password
}))

I tested this change locally by just using Promise.resolve e.g.

module.exports = Promise.resolve({
	host: 'localhost',
	database: 'my_sweet_app',
	user: 'testuser',
	pass: 'somepass'
})

[lukeed]

I don't really know why but those examples give me the heebie jeebies haha. It feels a bit off to do module.exports = Promise, even though module.exports = async function () {} is exactly the same thing and feels fine to me. 🤷

[TehShrike]

hah, yeah, I can understand that. Taste could easily drive you to

module.exports = async () => {
	const { db_user, db_password } = await import('./environment.mjs')

	return {
		host: 'localhost',
		database: 'my_sweet_app',
		user: db_user,
		pass: db_password
	}
}

I put the await on the outside because I figured allowing either version was the reasonable thing to do.