fix(checkout): load custom CSS for block forms (#1666)

[superdav42]

Summary

• Preserve checkout block and shortcode attributes while rendering, including the configured form slug.
• Use that slug when compiling and attaching the form's scoped Custom CSS.
• Add regression coverage that creates a form with Custom CSS and verifies the generated inline style.

Verification

• vendor/bin/phpcs inc/ui/class-checkout-element.php tests/WP_Ultimo/UI/Checkout_Element_Test.php
• vendor/bin/phpstan analyse inc/ui/class-checkout-element.php
• vendor/bin/phpunit --filter Checkout_Element_Test

Known baseline failures

• npm run check stops at existing JavaScript lint errors in unrelated assets.
• npm run stan reports 526 existing errors outside the changed files.
• npm run test completes 10,124 tests with 2 existing Site Exporter errors and 1 existing discount-code assertion failure.

Resolves #1666

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aidevops.sh v3.32.188 plugin for OpenCode v1.18.5 with gpt-5.6-terra

Summary by CodeRabbit

• Bug Fixes

  • Checkout forms now retain their configured slug when assets are registered later.
  • Custom checkout styling is applied consistently to the correct form.

• Tests

  • Added coverage verifying slug retention and generated custom stylesheet behavior.

[coderabbitai]

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 25db0a75-6f00-4494-9764-48ceda12bd70

📥 Commits

Reviewing files that changed from the base of the PR and between da25e67 and 71a5d4b.

📒 Files selected for processing (2)

• inc/ui/class-checkout-element.php
• tests/WP_Ultimo/UI/Checkout_Element_Test.php

📝 Walkthrough

Walkthrough

Checkout_Element now retains merged display attributes for later script registration, uses a default slug fallback, and includes a regression test verifying slug retention and generated custom CSS output.

Changes

Checkout custom CSS

Layer / File(s)	Summary
Retain checkout attributes for script registration inc/ui/class-checkout-element.php	display() stores merged attributes before calling the parent implementation, while register_scripts() falls back to the default checkout slug.
Verify slug-scoped custom CSS tests/WP_Ultimo/UI/Checkout_Element_Test.php	The test verifies retained slugs and the presence of the slug-scoped custom CSS selector in registered stylesheet data.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly states the checkout block Custom CSS fix and matches the change set.
Linked Issues check	✅ Passed	The changes preserve the checkout slug for rendering and add regression coverage for inline Custom CSS, satisfying #1666.
Out of Scope Changes check	✅ Passed	The PR stays focused on checkout slug handling and Custom CSS output, with only a targeted regression test added.
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
• Commit unit tests in branch bugfix/gh1666-reproduce-and-fix-checkout-custom-css-is

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[github-actions]

🔨 Build Complete - Ready for Testing!

📦 Download Build Artifact (Recommended)

Download the zip build, upload to WordPress and test:

• Build: ultimate-multisite
• ⬇️ Download from GitHub Actions
• ⬇️ Download without Github Account (nightly.link)

🌐 Test in WordPress Playground (Very Experimental)

Click the link below to instantly test this PR in your browser - no installation needed!
Playground support for multisite is very limitied, hopefully it will get better in the future.

🚀 Launch in Playground

Login credentials: admin / password

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@inc/ui/class-checkout-element.php`:
- Line 369: Update the slug resolution in the checkout element flow around
get_pre_loaded_attribute() so a false or unavailable pre-loaded attribute falls
back to the configured default slug before calling
wu_get_checkout_form_by_slug(). Preserve valid pre-loaded slugs, and add a
regression test covering execution without a prior display() call.

In `@tests/WP_Ultimo/UI/Checkout_Element_Test.php`:
- Around line 72-96: Update the test around the Checkout_Element singleton
mutation to save the original pre_loaded_attributes value, then wrap display and
subsequent assertions/setup in a try/finally block. In finally, remove the
wu_checkout_skip_output filter and restore the saved property value so
exceptions cannot leak shared state into later tests.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: d7ab9b72-db14-45cb-aff3-c8e5b2b6a354

📥 Commits

Reviewing files that changed from the base of the PR and between 1238102 and da25e67.

📒 Files selected for processing (2)

• inc/ui/class-checkout-element.php
• tests/WP_Ultimo/UI/Checkout_Element_Test.php

[superdav42]

Addressed the review findings in 71a5d4be:

• register_scripts() now explicitly falls back to main-form when the pre-loaded slug is unavailable.
• Added coverage for script registration without a preceding display() call.
• Wrapped singleton state and filter mutation in try/finally cleanup.

Verified with targeted PHPCS, PHPStan, and Checkout_Element_Test (6 tests, 29 assertions).

---

aidevops.sh v3.32.188 plugin for OpenCode v1.18.5 with gpt-5.6-terra

[github-actions]

🔨 Build Complete - Ready for Testing!

📦 Download Build Artifact (Recommended)

Download the zip build, upload to WordPress and test:

• Build: ultimate-multisite
• ⬇️ Download from GitHub Actions
• ⬇️ Download without Github Account (nightly.link)

🌐 Test in WordPress Playground (Very Experimental)

Click the link below to instantly test this PR in your browser - no installation needed!
Playground support for multisite is very limitied, hopefully it will get better in the future.

🚀 Launch in Playground

Login credentials: admin / password

[github-actions]

Performance Test Results

Performance test results for 7b660c6 are in 🛎️!

[superdav42]

Maintainer Approval (cryptographically signed)

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