Add validation for font-faces property

[louwers]

Closes #1350

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.68%. Comparing base (4255ad2) to head (490050c).

Files with missing lines	Patch %	Lines
src/validate/validate_font_faces.ts	90.47%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1351      +/-   ##
==========================================
- Coverage   93.70%   93.68%   -0.02%     
==========================================
  Files         110      111       +1     
  Lines        4368     4389      +21     
  Branches     1386     1390       +4     
==========================================
+ Hits         4093     4112      +19     
- Misses        275      277       +2     

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[github-actions]

Size Change: +537 B (+0.4%)

Total Size: 134 kB

Filename	Size	Change
dist/index.cjs	67.5 kB	+267 B (+0.4%)
dist/index.mjs	66.5 kB	+270 B (+0.41%)

_{compressed-size-action}

[HarelM]

Added a few minor comments.

[Copilot]

Pull Request Overview

This PR adds validation support for the font-faces property in style specifications. The font-faces property allows specifying custom font files for rendering text with different formats (string URLs or arrays of font face objects with unicode ranges).

• Introduces a new validateFontFaces function to validate the font-faces property structure
• Updates the schema to change font-faces type from array with value: "fontFaces" to a single custom type fontFaces
• Adds comprehensive integration tests covering valid and invalid font-faces configurations

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/validate/validate_font_faces.ts	New validator function for font-faces property that validates object structure, string URLs, and arrays of font face objects
src/validate/validate.ts	Registers the new validateFontFaces validator in the VALIDATORS mapping
src/reference/v8.json	Updates font-faces schema from array type to custom fontFaces type
build/generate-docs.ts	Adds fontfaces case to map to font-faces.md documentation
test/integration/style-spec/tests/*.json	Adds 10 test files covering validation scenarios for invalid types (string, number, boolean, array) and valid structures (empty object, string URL, array of font faces)

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[Copilot]

Using the general Function type is not type-safe. Consider using a more specific function signature or importing the correct type from the codebase, similar to how other validators handle this parameter.

Suggested change

	interface ValidateFontFacesOptions {
	key: string;
	value: unknown;
	styleSpec: typeof v8;
	style: StyleSpecification;
	validateSpec: Function;
	import type {ValidationError} from '../error/validation_error';
	interface ValidateFontFacesOptions {
	key: string;
	value: unknown;
	styleSpec: typeof v8;
	style: StyleSpecification;
	validateSpec: (options: { key: string; value: unknown; styleSpec: typeof v8; style: StyleSpecification; }) => ValidationError[];

[Copilot]

Using any[] cast bypasses type safety. Since fontValueType === 'array' was already checked on line 46, consider using Array<unknown> instead of any[] for better type safety.

Suggested change

	for (const [i, fontFace] of (fontValue as any[]).entries()) {
	for (const [i, fontFace] of (fontValue as Array<unknown>).entries()) {