Issue #3248440 by lauriii, Wim Leers, nod_: [drupalMedia] Media embed...

Issue #3248440 by lauriii, Wim Leers, nod_: [drupalMedia] Media embed attributes are rendered in container div in editing view

core/modules/ckeditor5/js/ckeditor5_plugins/drupalMedia/src/drupalmediaediting.js

@@ -248,7 +248,7 @@ export default class DrupalMediaEditing extends Plugin {
 
     // Set attributeToAttribute conversion for all supported attributes.
     Object.keys(this.attrs).forEach((modelKey) => {
-      conversion.attributeToAttribute({
+      const attributeMapping = {
         model: {
           key: modelKey,
           name: 'drupalMedia',
@@ -257,7 +257,11 @@ export default class DrupalMediaEditing extends Plugin {
           name: 'drupal-media',
           key: this.attrs[modelKey],
         },
-      });
+      };
+      // Attributes should be rendered only in dataDowncast to avoid having
+      // unfiltered data-attributes on the Drupal Media widget.
+      conversion.for('dataDowncast').attributeToAttribute(attributeMapping);
+      conversion.for('upcast').attributeToAttribute(attributeMapping);
     });
   }
 

core/modules/ckeditor5/tests/src/FunctionalJavascript/MediaTest.php

@@ -347,6 +347,9 @@ public function testAlt() {
     // Assert that the img within the media embed within the CKEditor contains
     // the overridden alt text set in the dialog.
     $this->assertNotEmpty($assert_session->waitForElementVisible('css', '.ck-widget.drupal-media img[alt*="' . $who_is_zartan . '"]'));
+    // Ensure that the Drupal Media widget doesn't have alt attribute.
+    // @see https://www.drupal.org/project/drupal/issues/3248440
+    $assert_session->elementNotExists('css', '.ck-widget.drupal-media[alt]');
     // Test `aria-label` attribute appears on the widget wrapper.
     $assert_session->elementExists('css', '.ck-widget.drupal-media [aria-label="Screaming hairy armadillo"]');