Add test utils to astro core

[natemoo-re]

Changes

• Still WIP, just opening a draft.
• Adds astro/test with some helpful utilities for testing Astro components

Testing

TODO

Docs

TODO

[changeset-bot]

⚠️ No Changeset found

Latest commit: 9450da4

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[matthewp]

It would be cool if this function also worked inside of .astro components, can we make this accept a non-JSX astro type? I'm thinking I'd love to be able to do:

src/components/Greeting.test.astro

---
import { expect, test } from 'vitest'
import { render } from 'astro/test'
import Greeting from './Greeting.astro'

test('Greeting', async () => {
	const { container } = await render(Greeting, { props: 'here' })
	expect(container).toBeDefined()
	expect(container.textContent).toBe('Hello world')
})
---

[matthewp]

I realize that the above probably doesn't work for some reasons, just noting that it would be nice if this generically named render function can be extended in the future for non-JSX test files.

[jasikpark]

:partyblob:

[matthewp]

This is stale so closing, please reopen if you're about to update it.

[omidantilong]

Hey @natemoo-re 👋 I've been digging into possible unit testing strategies for Astro... Just wondering what happened with this PR, it looked promising!

[natemoo-re]

Hey @natemoo-re 👋 I've been digging into possible unit testing strategies for Astro... Just wondering what happened with this PR, it looked promising!

Hey, thanks for asking! This is something we're interested in circling back to. We were originally blocked by the lack of a user-facing API for rendering Astro components to a string. Internally, it required the full Request and a decent amount of other metadata. We've accepted a proposal to implement that feature, but haven't had the bandwidth for it until recently. Once that is implemented, what this PR explored should land in one form or another.

The proposal actually came out of this exploration specifically. Hoping to implement in early 2024!

withastro/roadmap#533

[omidantilong]

Thanks for the quick reply man! Just to be clear, did the original proposal in this PR actually work? I assume the issue around the Request and accompanying metadata etc is what the createResult call is for. I'm just curious if you managed to get it working (even halfway) because it looks like it should, but when I tried to shoehorn it into my little sandbox project I just got Vite complaining (via Vitest) about not being able to parse the source because it's invalid syntax.

Really hopeful to see progress on 533 and would love to contribute if I can, hence all this poking around (at 11.30pm on Christmas Eve 🎄 )