Sandbox::https://github.com/uswds/uswds/pull/6975

Raydman · 2026-09-18T15:39:33Z

Summary

Cover the web component banner in the existing unit suite. usa-banner.component.js had no tests in this repo. A Mocha spec now exercises it under jsdom, and a small Node loader hook lets Mocha import the Lit component without adding vitest or a build step.

Breaking change

This is not a breaking change. No component, CSS, markup, or dependency changed. The new require entry in .mocharc.json only registers loader hooks and a customElements global, and it is inert for every existing spec.

Related issue

Closes #6470.

Problem and solution

The component is authored for Vite. It imports _index.scss?inline and _usa-banner.component.css?inline as strings and three images as URLs, which Node cannot load, so import "../usa-banner.component.js" failed under Mocha with Unknown file extension ".scss". The Elements repo covered this with vitest, and the issue rules out bringing vitest along.

register-web-components.js runs from the shared .mocharc.json after jsdom-global/register. It registers web-component-hooks.mjs through node:module's register(), whose resolve hook answers ?inline specifiers with an empty string module and image specifiers with their file name, and it copies customElements from the jsdom window onto global, which jsdom-global does not expose. Without that global, Lit's Node build installs its own SSR shim registry and elements created through jsdom never upgrade.

Two alternatives were checked and dropped. Forcing Lit's browser export condition is unnecessary because Lit's Node build already adopts a global HTMLElement and customElements when they exist, and the spec passes identically on either build. Building the CDN bundle first and testing the output would tie a unit test to a Vite build and belongs with distTests, not the unit runner.

The spec mirrors the existing banner.spec.js structure and covers the toggle in both directions, English and Spanish strings with fallback for an unknown lang, .gov and .mil guidance with fallback for an unknown tld, reflection of lang and tld to the host, the label override and the banner-action slot, and the decorative image, lock icon, and button type attributes. This is a superset of the six cases in the Elements vitest spec.

Major changes

packages/usa-banner/src/test/usa-banner.component.spec.mjs: new spec, 18 cases.
packages/uswds-core/src/js/utils/test/web-component-hooks.mjs: resolve hook for ?inline and image imports.
packages/uswds-core/src/js/utils/test/register-web-components.js: registers the hook and exposes customElements.
packages/uswds-core/src/js/utils/test/.mocharc.json: requires the register file.
tasks/test.js: SPEC_FLOOR 77 to 78.

Validation

Node 22.23.1, with CI on cimg/node:24.16.0. module.register needs Node 20.6, and importing the component's ESM .js file relies on module syntax detection, unflagged in Node 20.19 and 22.7; both are inside the supported range.

npx gulp test: passes (spec count 78, typecheck, 128 Sass, 948 component, 71 tooling).
Negative controls, each run with --no-config so the root .mocharc.js cannot reload the real setup: without the hook the spec fails on the .scss import; without the customElements global it fails with customElements is not defined on the browser build and 17 of 18 cases fail on the Node build because the element never upgrades.
npx eslint .: 0 errors. The no-underscore-dangle warnings are pre-existing and identical on develop.
npx prettier -c passes on all five files.

No component behavior changed, so no accessibility testing is claimed for this change.

github-actions · 2026-09-18T15:39:44Z

✅ All commits on this PR have a verified signature. Thanks!

coderabbitai · 2026-09-18T15:39:49Z

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packages/uswds-core/src/js/utils/test/register-web-components.js
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📝 Summary

Summary by CodeRabbit

Tests
- Expanded coverage for the USA banner’s expand/collapse behavior, English and Spanish text, language and domain settings, custom content, and accessibility.
- Improved validation of web-component behavior and asset handling in the test environment.
- Increased the minimum number of test files required for checks to pass.

Walkthrough

The pull request adds usa-banner web-component tests to the existing test suite. It also configures Mocha’s Node.js module loading for component files and related assets, and raises the minimum discovered spec-file count.

Changes

usa-banner testing

Layer / File(s)	Summary
Web-component test runtime `packages/uswds-core/src/js/utils/test/.mocharc.json`, `packages/uswds-core/src/js/utils/test/register-web-components.js`, `packages/uswds-core/src/js/utils/test/web-component-hooks.mjs`	Mocha loads a setup module that requires Node 20.6 or newer, registers a module-resolution hook, and exposes jsdom’s `customElements` registry globally. The hook supplies modules for `?inline` stylesheets and supported image assets, and marks resolved `.component.js` files as ES modules.
usa-banner behavior coverage `packages/usa-banner/src/test/usa-banner.component.spec.mjs`, `tasks/test.js`	Tests cover component registration, expand and collapse behavior, localization, TLD guidance, author overrides, and accessibility attributes. The test task now requires at least 78 discovered spec files.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Other

Suggested labels: Context: JavaScript, Affects: Testing, Affects: Compiling

Merge Risk: ⚪ Minimal · up to b86fd

The new tests require a newer Node version than the published package does. Contributors using the documented Node version can run them, so this does not prevent merging.

🚥 Pre-merge checks | ✅ 10

✅ Passed checks (10 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows the required format and describes the added banner web component tests.
Description check	✅ Passed	The description explains the banner tests, the Mocha and Node loader setup, and the related validation. It is directly related to the changeset.
Linked Issues check	✅ Passed	Issue `#6470` asks for `usa-banner` web-component tests in the existing test suite, without adding Vitest. The PR adds an 18-case Mocha spec and the loader setup needed to import the component under tha…
Out of Scope Changes check	✅ Passed	The Mocha loader hook, jsdom `customElements` setup, and spec-floor update support the tests requested by issue `#6470`. The current PR description and change summary report no component, CSS, markup, d…
Breaking Change Declared	✅ Passed	The PR description contains exactly one template statement: “This is not a breaking change.” The reviewed diff changes only a new component test, Mocha test setup files, and the test spec-count floor.…
No New Runtime Dependency	✅ Passed	The PR changes no package.json files, so the dependencies field is unchanged. The added imports and require calls are in test files or test setup under packages//src//test/**; the diff adds no pro…
Regression Test Targets The Change	✅ Passed	The check is not applicable. The PR changes only the new banner spec, Mocha test setup and hooks under `packages//test/`, and the test-count task. The only changed `.js` file under `packages//src/…
New Api Surface Follow-Ups	✅ Passed	The check does not apply. The PR adds a test file and test-loader configuration, and changes the test-count threshold. It does not add a theme setting, forwarded Sass mixin or function, data-attribute…
Accessibility Verification Declared	✅ Passed	The check does not apply. The reviewed diff adds tests that assert existing ARIA attributes, but it does not change the component’s ARIA attributes, focus management, keyboard handling, screen reader …
Theme Token Discipline	✅ Passed	No SCSS files under packages/ changed in this pull request. The token-discipline check does not apply.

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Actionable comments posted: 1

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Inline comments:
In `@packages/uswds-core/src/js/utils/test/register-web-components.js`:
- Line 4: Update the project’s Node engine constraint to require Node 20.6.0 or
newer, matching the module.register usage in register-web-components.js.
Preserve the existing loader behavior rather than adding an alternate path.

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📒 Files selected for processing (5)

packages/usa-banner/src/test/usa-banner.component.spec.mjs
packages/uswds-core/src/js/utils/test/.mocharc.json
packages/uswds-core/src/js/utils/test/register-web-components.js
packages/uswds-core/src/js/utils/test/web-component-hooks.mjs
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ryparker · 2026-09-25T14:50:46Z

The new tests also raise the minimum Node version for the published package. The engine requirement changes from >=20 to >=20.6.0, so Node 20.0 through 20.5 no longer satisfy it. Projects that enforce package engine requirements can fail installation after upgrading, even if they never run the banner tests. I added the breaking label for that support change.

If the newer Node version is needed only for the test loader, we could keep the published engine range and handle the test requirement separately. Otherwise, the PR's breaking-change section should tell teams to upgrade Node to at least 20.6.0.

Raydman · 2026-09-25T17:43:15Z

@ryparker Thanks, good catch. The 20.6 requirement was only for the Mocha loader hook, not the published package, so I reverted the engines change and kept >=20. The test setup now checks for module.register() and fails with a clear message on older Node. It also declares the component files as ESM, so the spec no longer depends on newer syntax detection. I verified it on Node 20.6.0 and 22. With the published range back to what's on develop, could the breaking label come off?

ajfarkas · 2026-10-06T19:02:34Z

@ryparker Thanks, good catch. The 20.6 requirement was only for the Mocha loader hook, not the published package, so I reverted the engines change and kept >=20. The test setup now checks for module.register() and fails with a clear message on older Node. It also declares the component files as ESM, so the spec no longer depends on newer syntax detection. I verified it on Node 20.6.0 and 22. With the published range back to what's on develop, could the breaking label come off?

I agree that this change works around the Node version issue. I've removed the breaking change label and will rebase and approve if everything looks good.

Register Node module hooks so Mocha can import the Lit component's `?inline` stylesheet and image asset imports, expose `customElements` from jsdom, and cover toggle, lang, tld, author overrides, and accessibility attributes in the existing unit suite.

Restore `engines.node` to ">=20". Only the Mocha loader needs `module.register()`, so the test setup now checks for it and names the required version instead of the published package demanding it. The resolve hook marks `*.component.js` as ESM so the component no longer relies on syntax detection (unflagged only in 20.19 and 22.7). The spec now runs on Node 20.6.0, and the MODULE_TYPELESS_PACKAGE_JSON warning is gone.

Raydman · 2026-10-06T19:22:12Z

Thanks for the rebase @ajfarkas! It dropped the commit signatures, so I re-signed the same commits on top of develop. The diff is unchanged. Ready for your review.

ajfarkas

Thank you, I appreciate the addition of these tests.

coderabbitai Bot reviewed Sep 18, 2026

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Comment thread packages/uswds-core/src/js/utils/test/register-web-components.js

ryparker added the Is: Breaking 🔴 Suggestion would be a breaking change label Sep 25, 2026

ajfarkas removed the Is: Breaking 🔴 Suggestion would be a breaking change label Oct 6, 2026

ajfarkas force-pushed the fix/6470-banner-component-tests branch from a886c14 to b86fd90 Compare October 6, 2026 19:02

github-actions Bot added the Needs: Author Response 🔴 Waiting on a specific author action; also used by commit-signature automation. label Oct 6, 2026

Raydman added 3 commits October 6, 2026 23:21

chore: require Node 20.6.0 for the module customization hooks

82a48c1

Raydman force-pushed the fix/6470-banner-component-tests branch from b86fd90 to e8a1028 Compare October 6, 2026 19:21

github-actions Bot removed the Needs: Author Response 🔴 Waiting on a specific author action; also used by commit-signature automation. label Oct 6, 2026

ajfarkas self-assigned this Oct 6, 2026

ajfarkas approved these changes Oct 6, 2026

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ajfarkas merged commit ec80133 into uswds:develop Oct 7, 2026
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ryparker mentioned this pull request Oct 15, 2026

fix(banner): resolve aria-controls in usa-banner web component #7011

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test(banner): add unit tests for web component variant - #6975

test(banner): add unit tests for web component variant#6975
ajfarkas merged 3 commits into
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Raydman:fix/6470-banner-component-tests

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Raydman commented Sep 18, 2026

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