Testing ActiveStorage attached file

[belgoros]

Are there any guidelines, examples on how to test ActiveStorage (model, request specs) ? I'm a little bit lost with all these new AS methods:

ActiveStorage::Blob.create_after_upload!
create_before_direct_upload
fixture_file_upload

My use case is really trivial:

class Post < ApplicationRecord
  serialize :tag_ids, Array
  validates :title, :body, :tag_ids, presence: true


  has_one_attached :photo
end

PostsController is just the one generated with scaffold.

Thank you.