Rule aliases in an inheriting policy don't override aliases in parent policies

[jacobwalkr]

Tell us about your environment

Ruby Version:
2.4.3 (in Docker)

Framework Version (Rails, whatever):
Rails 5.2.0.rc2

Action Policy Version:
0.2.0

What did you do?

class ApplicationPolicy < ActionPolicy::Base; end

class GroupPolicy < ApplicationPolicy
  def new?
    user.staff?
  end
  alias_rule :create?, to: :new?
end

What did you expect to happen?

For GroupPolicy#create? to be aliased to GroupPolicy#new?

What actually happened?

GroupPolicy#create? was actually still aliased to ActionPolicy::Base#new? (because of the alias_rule :create, to: :new? in ActionPolicy::Policy::Defaults, I think) and so always returned false. The solution was to define another create? method that called new? explicitly.

(Sorry, I accidentally submitted this before I'd finished it)

[palkan]

Aliases should be overridable (see this test: https://github.com/palkan/action_policy/blob/master/test/action_policy/policy/aliases_test.rb#L52).

Could you, please, provide the output for: GroupPolicy.new(user: User.new).resolve_rule(:new?) ?

[jacobwalkr]

irb(main):012:0> GroupPolicy.new(user: User.new).resolve_rule(:new?)
=> :index?
irb(main):013:0> GroupPolicy.new(user: User.new).resolve_rule(:create?)
=> :create?

This is with defaults included in the ApplicationPolicy and this GroupPolicy:

class GroupPolicy < ApplicationPolicy
  def index?
    true
  end
  alias_rule :new?, :create?, :edit?, :update?, to: :index?
end

[jacobwalkr]

I tried the other routes for fun:

irb(main):014:0> GroupPolicy.new(user: User.new).resolve_rule(:index?)
=> :index?
irb(main):015:0> GroupPolicy.new(user: User.new).resolve_rule(:edit?)
=> :index?
irb(main):016:0> GroupPolicy.new(user: User.new).resolve_rule(:update?)
=> :index?
irb(main):017:0> GroupPolicy.new(user: User.new).resolve_rule(:destroy?)
=> :default_rule
irb(main):018:0> GroupPolicy.new(user: User.new).resolve_rule(:show?)
=> :default_rule

default_rule is defined in our ApplicationPolicy.

[jacobwalkr]

If I remove defaults from ApplicationPolicy:

irb(main):025:0> GroupPolicy.new(user: User.new).resolve_rule(:create?)
=> :index?

[brendon]

I've hit this too. It seems the idea is that if a hard rule has been defined in a superclass, an alias_rule in a subclass has no effect.

[jacobwalkr]

Thanks for your work, guys. This is super helpful and I wouldn't have known where to start 😊

[brendon]

You're most welcome :) Now I know a lot about action_policy! :D