Matcher for readonly fields #220
Description
Similar to the mass-assignment matchers, but for https://api.rubyonrails.org/v5.1/classes/ActiveRecord/ReadonlyAttributes/ClassMethods.html
{{ message }}
Similar to the mass-assignment matchers, but for https://api.rubyonrails.org/v5.1/classes/ActiveRecord/ReadonlyAttributes/ClassMethods.html