Add unit tests for color and utils libraries

[alekslinde]

Summary

• color.ts and utils.ts had no test coverage despite being used by multiple tools (WCAG contrast checker, tints/shades, color palette, font converter). This adds 59 tests covering all exported pure functions.
• dl is intentionally excluded — it requires DOM APIs and is untestable in the Node Vitest environment.
• All 102 tests pass (59 new + 43 existing font-converter tests).

Test plan

• npm test → all 102 tests green
• fmtBytes — byte/KB/MB boundary values produce correct formatted strings
• baseName / extOf — multi-part names, hidden files, no-extension inputs
• hexToRgb / rgbToHex — 3-digit shorthand expansion, round-trip fidelity
• rgbToHsl / hslToRgb — primary colors, black, white, grey, round-trip within rounding tolerance
• relativeLuminance — black=0, white=1, output in [0,1]
• contrastRatio — black/white ≈21:1, symmetry, WCAG AA threshold (≥4.5)
• isLight — white/yellow light; black/navy dark
• isValidHex — accepts #rgb and #rrggbb; rejects missing hash, wrong length, invalid chars
• mixColors — t=0 returns first color, t=1 returns second, t=0.5 midpoint, known interpolation value

[cloudflare-workers-and-pages]

Deploying with    Cloudflare Workers

The latest updates on your project. Learn more about integrating Git with Workers.

Status	Name	Latest Commit	Updated (UTC)
❌ Deployment failed View logs	lindetoolbox	e532720	Jun 11 2026, 01:54 PM