Since we're skipping the example in a before hook, the @_subscribers
instance variable that is normally set in the setup phase of the test by
https://github.com/rails/rails-controller-testing/blob/21014e48be124dd8d0af250b79f682519d445015/lib/rails/controller/testing/template_assertions.rb#L21
isn't set but the teardown phase of the example still happens and tries
to iterate over the array of subcribers: https://github.com/rails/rails-controller-testing/blob/21014e48be124dd8d0af250b79f682519d445015/lib/rails/controller/testing/template_assertions.rb#L54

Using an around hook allows the @_subscribers instance variable to be
set.
Signed-off-by: Rémy Coutable <remy@rymai.me>