fix(#19): address round-2 Copilot review (doc + test polish)

Author: johanrd

docs/rules/template-no-aria-hidden-on-focusable.md

@@ -12,6 +12,10 @@ Per [WAI-ARIA 1.2 — aria-hidden](https://www.w3.org/TR/wai-aria-1.2/#aria-hidd
 
 The phrase "may receive focus" is interpreted to include focusable descendants: `aria-hidden` cascades to hide the entire subtree from assistive tech, while any focusable descendant within that subtree remains reachable via Tab — landing keyboard users on AT-invisible content.
 
+### What counts as `aria-hidden="true"`
+
+Only explicit truthy values trigger the rule: `aria-hidden="true"`, `aria-hidden={{true}}`, `aria-hidden="{{true}}"`, and case-insensitive variants. Valueless `<div aria-hidden>` and `aria-hidden="false"` / `{{false}}` are NOT treated as hidden — the author's signal must be explicit. See the shared spec-divergence rationale in `template-no-invalid-interactive` for the broader reasoning on valueless `aria-hidden` handling across this plugin.
+
 ## Examples
 
 This rule **forbids** the following:

lib/rules/template-no-aria-hidden-on-focusable.js

@@ -160,7 +160,8 @@ module.exports = {
   meta: {
     type: 'problem',
     docs: {
-      description: 'disallow aria-hidden="true" on focusable elements',
+      description:
+        'disallow aria-hidden="true" on focusable elements or on ancestors of focusable descendants',
       category: 'Accessibility',
       url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-aria-hidden-on-focusable.md',
       templateMode: 'both',

tests/lib/rules/template-no-aria-hidden-on-focusable.js

@@ -59,7 +59,7 @@ ruleTester.run('template-no-aria-hidden-on-focusable', rule, {
     '<template><div aria-hidden="true"><span>Just text</span></div></template>',
     // Component descendants are opaque — conservatively not flagged.
     '<template><div aria-hidden="true"><Button>X</Button></div></template>',
-    // No focusable descendants (alt-less img is decorative, not focusable).
+    // <img> without usemap is non-focusable regardless of alt text.
     '<template><div aria-hidden="true"><img alt="static" /></div></template>',
     // <input type="hidden"> is non-focusable per isFocusable.
     '<template><div aria-hidden="true"><input type="hidden" /></div></template>',

tests/lib/utils/is-native-element-test.js

@@ -80,12 +80,20 @@ describe('isNativeElement — list-only behavior (no sourceCode)', () => {
 });
 
 describe('ELEMENT_TAGS', () => {
-  it('includes all HTML, SVG, and MathML tag names', () => {
-    // Sanity check — if this ever drops below a reasonable size, one of the
-    // underlying packages has changed contract.
-    expect(ELEMENT_TAGS.size).toBeGreaterThan(200);
-    expect(ELEMENT_TAGS.has('div')).toBe(true);
-    expect(ELEMENT_TAGS.has('circle')).toBe(true);
-    expect(ELEMENT_TAGS.has('mfrac')).toBe(true);
+  it('includes representative HTML, SVG, and MathML tag names', () => {
+    // Spot-check one tag per source package rather than pinning a count,
+    // which drifts whenever html-tags / svg-tags / mathml-tag-names ship
+    // new entries.
+    expect(ELEMENT_TAGS.has('div')).toBe(true); // html-tags
+    expect(ELEMENT_TAGS.has('button')).toBe(true);
+    expect(ELEMENT_TAGS.has('circle')).toBe(true); // svg-tags
+    expect(ELEMENT_TAGS.has('path')).toBe(true);
+    expect(ELEMENT_TAGS.has('mfrac')).toBe(true); // mathml-tag-names
+    expect(ELEMENT_TAGS.has('msqrt')).toBe(true);
+  });
+
+  it('excludes non-tags', () => {
+    expect(ELEMENT_TAGS.has('MyComponent')).toBe(false);
+    expect(ELEMENT_TAGS.has('my-widget')).toBe(false);
   });
 });