Adjust testing docs

Clarify a little confusion
around using a class name for
selecting a dom element.

doc/development/testing_guide/frontend_testing.md

@@ -204,11 +204,11 @@ Following you'll find some general common practices you will find as part of our
 
 ### How to query DOM elements
 
-When it comes to querying DOM elements in your tests, it is best to uniquely target the element, without adding additional attributes specifically for testing purposes. Sometimes this cannot be done feasibly. In these cases, adding test attributes to simplify the selectors might be the best option.
+When it comes to querying DOM elements in your tests, it is best to uniquely and semantically target the element. Sometimes this cannot be done feasibly. In these cases, adding test attributes to simplify the selectors might be the best option.
 
 Preferentially, in component testing with `@vue/test-utils`, you should query for child components using the component itself. This helps enforce that specific behavior can be covered by that component's individual unit tests. Otherwise, try to use:
 
-- A behavioral attribute like `name` (also verifies that `name` was setup properly)
+- A semantic attribute like `name` (also verifies that `name` was setup properly)
 - A `data-testid` attribute ([recommended by maintainers of `@vue/test-utils`](https://github.com/vuejs/vue-test-utils/issues/1498#issuecomment-610133465))
 - a Vue `ref` (if using `@vue/test-utils`)
 
@@ -216,11 +216,17 @@ Examples:
 
 ```javascript
 it('exists', () => {
+    // Good
     wrapper.find(FooComponent);
     wrapper.find('input[name=foo]');
     wrapper.find('[data-testid="foo"]');
     wrapper.find({ ref: 'foo'});
+
+    // Bad
     wrapper.find('.js-foo');
+    wrapper.find('.btn-primary');
+    wrapper.find('.qa-foo-component');
+    wrapper.find('[data-qa-selector="foo"]');
 });
 ```