Fonts: fix typing for disabled fallbacks (empty array)

[altano]

Changes

Regarding experimental fonts, the documentation says:

To disable fallback fonts completely, configure an empty array:

fallbacks: []

But I get a Typescript error if I do that. This is a simple typing issue, not a behavioral one, so in this PR I am:

• fixing the type so an empty array is allowed, to match the doc

Closes #13659

Testing

Added a type test that fails before this change and succeeds after:

BEFORE:

$ pnpm test:types
test/types/define-config.ts:150:8 - error TS2322: Type '[]' is not assignable to type '[string, ...string[]]'.
Source has 0 element(s) but target requires 1.

150 fallbacks: [],
~~~~~~~~~

AFTER:

$ pnpm test:types
succeeds

Docs

Bringing types in line with docs, no doc updates needed

[changeset-bot]

🦋 Changeset detected

Latest commit: 00926a2

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[codspeed-hq]

CodSpeed Performance Report

Merging #13681 will not alter performance

_{Comparing altano:fonts-fix-fallbacks-type (00926a2) with main (6ed8360)}

Summary

✅ 6 untouched benchmarks

[ematipico]

I'm not sure about the nature of this fix. I recall that having an empty array for fallback must be an error. Do we have a configuration test for this case? Can you check @altano, and make sure that fallback: [] throws an error?

cc @florian-lefebvre

[florian-lefebvre]

Thanks for the PR! Can you also add a test case here? https://github.com/withastro/astro/blob/main/packages/astro/test/units/config/config-validate.test.js#L391

[florian-lefebvre]

@ematipico empty fallbacks should not throw an error, this is a proper bug

[altano]

Can you also add a test case here?

Done, PR updated. But let me know if you had something more in mind, as I just added a basic "validateConfig shouldn't throw for empty fallbacks array" as a test:

assert.doesNotThrow(() =>
	validateConfig({
		experimental: {
			fonts: [
				{
					provider: fontProviders.google(),
					name: 'Roboto',
					fallbacks: [],
					cssVariable: '--font-roboto',
				},
			],
		},
	}),
);

[florian-lefebvre]

Thanks!