LayoutTests/accessibility/custom-elements/autocomplete.html

<!DOCTYPE html>
<html>
<body id="body">
<script src="../../resources/js-test.js"></script>
<script src="../../resources/accessibility-helper.js"></script>
<custom-list id="custom-list"></custom-checkbox>
<custom-list id="custom-textbox" role="textbox" aria-autocomplete="inline"></custom-checkbox>
<script>

customElements.define('custom-list', class CustomElement extends HTMLElement {
    constructor()
    {
        super();
        const internals = this.attachInternals();
        internals.role = 'combobox';
        internals.ariaAutoComplete = 'list';
    }
});

description("This tests that aria fallback roles work correctly.");
if (!window.accessibilityController)
    debug('This test requires accessibilityController');
else {
    shouldBeEqualToString('accessibilityController.accessibleElementById("custom-list").role', 'AXRole: AXComboBox');
    shouldBeEqualToString('accessibilityController.accessibleElementById("custom-list").stringAttributeValue("AXAutocompleteValue")', 'list');
    shouldBeEqualToString('accessibilityController.accessibleElementById("custom-textbox").role', 'AXRole: AXTextField');
    shouldBeEqualToString('accessibilityController.accessibleElementById("custom-textbox").stringAttributeValue("AXAutocompleteValue")', 'inline');
}

</script>
</body>
</html>