tests: minor cleanup (#35138)

* tests: minor cleanup

* tests: use the util noop function

js/tests/unit/button.spec.js

@@ -1,11 +1,5 @@
 import Button from '../../src/button'
-
-/** Test helpers */
-import {
-  getFixture,
-  clearFixture,
-  jQueryMock
-} from '../helpers/fixture'
+import { getFixture, clearFixture, jQueryMock } from '../helpers/fixture'
 
 describe('Button', () => {
   let fixtureEl