test(fonts): mock google font files in unit tests

[NathanDrake2406]

Fixes #2411

Overview

The Google font self-hosting unit tests now mock both the CSS request to fonts.googleapis.com and the font binary request to fonts.gstatic.com.

Why

The flaky CI failure was a real test isolation bug. The plugin intentionally treats raw Google Fonts fetch failures as recoverable offline behavior and skips _vinext.font injection, but this unit test expected deterministic self-hosted output while relying on external network availability.

What changed

• Added an MSW helper for Google font file responses.
• Mocked Google CSS and .woff2 responses in the self-hosting transform test.
• Mocked the same responses in the fetch/cache integration test so it still proves downloaded .woff2 cache output without external network.

Validation

• for i in 1 2 3 4 5; do vp test run tests/font-google.test.ts || exit $?; done
• vp check tests/font-google.test.ts

Note: local pre-commit was run and its staged file check passed, but its broad repo check failed in this fresh worktree because packages/vinext/node_modules/react-dom was not linked. The targeted checks above passed against the changed file.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vinext/cloudflare@2412

npm i https://pkg.pr.new/vinext@2412

commit: 60cbe52

[github-actions]

Performance benchmarks

Compared 60cbe52 against base 25f3d09 using alternating same-runner rounds. Next.js was unchanged and skipped.

0 improved · 0 regressed · 6 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	124.0 KB	124.0 KB	⚫ +0.0%
Client entry size (gzip)	vinext	118.8 KB	118.8 KB	⚫ +0.0%
Dev server cold start	vinext	2.41 s	2.42 s	⚫ +0.2%
Production build time	vinext	2.82 s	2.81 s	⚫ -0.3%
RSC entry closure size (gzip)	vinext	95.2 KB	95.2 KB	⚫ +0.0%
Server bundle size (gzip)	vinext	161.4 KB	161.5 KB	⚫ +0.0%

View detailed results and traces

_{🟢 improvement · 🔴 regression · ⚫ change below 1.5% · paired base/head}