Use .blue() instead of .b() in textColorForBackgroundColor

[thomasjlee]

Supersedes #905 which has been inactive for a few months

Color.b() returns the b (blue-yellow) LAB color space value of the color instance. It should instead return the blue value in hexadecimal.

The only change was made in packages/color-utils/src/color-utils.ts. I then ran:

• cd packages/color-utils && yarn build
• yarn test (in the root)

The deleted test was incorrectly asserting the buggy behavior. The remaining tests seem to provide sufficient coverage.

• There's a clear use-case for this code change
• Commit message has a short title & references relevant issues
• The build will pass (run yarn test and yarn lint)

I believe this will also fix TryGhost/Ghost#27797.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Configuration used: Organization UI

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Run ID: 4b407af3-9aad-459e-89a4-e5d835e5f0eb

📥 Commits

Reviewing files that changed from the base of the PR and between f6085ce and bb1d2cf.

⛔ Files ignored due to path filters (3)

• packages/color-utils/es/color-utils.js.map is excluded by !**/*.map
• packages/color-utils/umd/color-utils.min.js is excluded by !**/*.min.js
• packages/color-utils/umd/color-utils.min.js.map is excluded by !**/*.map, !**/*.min.js.map

📒 Files selected for processing (4)

• packages/color-utils/cjs/color-utils.js
• packages/color-utils/es/color-utils.js
• packages/color-utils/src/color-utils.ts
• packages/color-utils/test/color-utils.test.js

💤 Files with no reviewable changes (1)

• packages/color-utils/test/color-utils.test.js

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Walkthrough

Updated textColorForBackgroundColor to use backgroundColor.blue() for the blue channel in the YIQ contrast calculation across source and generated builds. Updated the test case from #cccccc to #333333, expecting white text.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Possibly related issues

• {{contrast_text_color}} helper returns incorrect text color Ghost#27797 — Fixes the .b() versus .blue() typo causing incorrect contrast text colors.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the primary fix to use blue() instead of b() in textColorForBackgroundColor.
Description check	✅ Passed	The description is directly related to the color utility bug fix, testing, and linked contrast-text-color issue.
Linked Issues check	✅ Passed	The source and distributable implementations replace b() with blue(), addressing the linked issue's identified YIQ contrast bug.
Out of Scope Changes check	✅ Passed	The implementation and test updates are focused on the linked contrast-color bug, with no unrelated code changes evident.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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