feat(field): add aria-live attribute to feedback slot

Author: marcosgilf

packages/field/src/FormControlMixin.js

@@ -139,6 +139,7 @@ export const FormControlMixin = dedupeMixin(
           }
         }
         if (_feedbackNode) {
+          _feedbackNode.setAttribute('aria-live', 'polite');
           _feedbackNode.id = _feedbackNode.id || `feedback-${this._inputId}`;
           const describeIdFeedback = ` ${_feedbackNode.id}`;
           if (this._ariaDescribedby.indexOf(describeIdFeedback) === -1) {

packages/field/test/FormControlMixin.test.js

@@ -62,4 +62,15 @@ describe('FormControlMixin', () => {
       expect(hasDuplicate).to.be.false;
     });
   });
+
+  it('adds aria-live="politie" to the feedback slot', async () => {
+    const lionField = await fixture(html`
+      <${tag}>
+        ${inputSlot}
+        <div slot="feedback">Added to see attributes</div>
+      </${tag}>
+    `);
+
+    expect(lionField.$$slot('feedback').getAttribute('aria-live')).to.equal('polite');
+  });
 });