Fix breaking change introduced in #204 (#614)

* Fix breaking change introduced in #204

* Fix

Co-authored-by: Fumiaki MATSUSHIMA <mtsmfm@gmail.com>

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Unreleased
 
+* [#571](https://github.com/CanCanCommunity/cancancan/pull/571): Allows to check ability even the object implements `#to_a`. ([@mtsmfm][])
 * [#612](https://github.com/CanCanCommunity/cancancan/pull/612): Suppress keyword arguments warning for Ruby 2.7.0. ([@koic][])
 
 ## 3.0.2
@@ -654,4 +655,5 @@ Please read the [guide on migrating from CanCanCan 2.x to 3.0](https://github.co
 [@kaspernj]: https://github.com/kaspernj
 [@frostblooded]: https://github.com/frostblooded
 [@eloyesp]: https://github.com/eloyesp
+[@mtsmfm]: https://github.com/mtsmfm
 [@koic]: https://github.com/koic

lib/cancan/relevant.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module CanCan
+  module Relevant
+    # Matches both the action, subject, and attribute, not necessarily the conditions
+    def relevant?(action, subject)
+      subject = subject.values.first if subject.class == Hash
+      @match_all || (matches_action?(action) && matches_subject?(subject))
+    end
+
+    private
+
+    def matches_action?(action)
+      @expanded_actions.include?(:manage) || @expanded_actions.include?(action)
+    end
+
+    def matches_subject?(subject)
+      @subjects.include?(:all) || @subjects.include?(subject) || matches_subject_class?(subject)
+    end
+
+    def matches_subject_class?(subject)
+      @subjects.any? do |sub|
+        sub.is_a?(Module) && (subject.is_a?(sub) ||
+            subject.class.to_s == sub.to_s ||
+            (subject.is_a?(Module) && subject.ancestors.include?(sub)))
+      end
+    end
+  end
+end

lib/cancan/rule.rb

@@ -1,12 +1,15 @@
 # frozen_string_literal: true
 
 require_relative 'conditions_matcher.rb'
+require_relative 'relevant.rb'
+
 module CanCan
   # This class is used internally and should only be called through Ability.
   # it holds the information about a "can" call made on Ability and provides
   # helpful methods to determine permission checking and conditions hash generation.
   class Rule # :nodoc:
     include ConditionsMatcher
+    include Relevant
     include ParameterValidators
     attr_reader :base_behavior, :subjects, :actions, :conditions, :attributes
     attr_writer :expanded_actions, :conditions
@@ -24,9 +27,9 @@ def initialize(base_behavior, action, subject, *extra_args, &block)
       raise Error, "Subject is required for #{action}" if action && subject.nil?
 
       @base_behavior = base_behavior
-      @actions = Array(action)
-      @subjects = Array(subject)
-      @attributes = Array(attributes)
+      @actions = wrap(action)
+      @subjects = wrap(subject)
+      @attributes = wrap(attributes)
       @conditions = extra_args || {}
       @block = block
     end
@@ -57,12 +60,6 @@ def catch_all?
         (!with_scope? && [nil, false, [], {}, '', ' '].include?(@conditions))
     end
 
-    # Matches both the action, subject, and attribute, not necessarily the conditions
-    def relevant?(action, subject)
-      subject = subject.values.first if subject.class == Hash
-      @match_all || (matches_action?(action) && matches_subject?(subject))
-    end
-
     def only_block?
       conditions_empty? && @block
     end
@@ -104,22 +101,6 @@ def matches_attributes?(attribute)
 
     private
 
-    def matches_action?(action)
-      @expanded_actions.include?(:manage) || @expanded_actions.include?(action)
-    end
-
-    def matches_subject?(subject)
-      @subjects.include?(:all) || @subjects.include?(subject) || matches_subject_class?(subject)
-    end
-
-    def matches_subject_class?(subject)
-      @subjects.any? do |sub|
-        sub.is_a?(Module) && (subject.is_a?(sub) ||
-          subject.class.to_s == sub.to_s ||
-          (subject.is_a?(Module) && subject.ancestors.include?(sub)))
-      end
-    end
-
     def parse_attributes_from_extra_args(args)
       attributes = args.shift if valid_attribute_param?(args.first)
       extra_args = args.shift
@@ -132,5 +113,15 @@ def condition_and_block_check(conditions, block, action, subject)
       raise BlockAndConditionsError, 'A hash of conditions is mutually exclusive with a block. '\
         "Check \":#{action} #{subject}\" ability."
     end
+
+    def wrap(object)
+      if object.nil?
+        []
+      elsif object.respond_to?(:to_ary)
+        object.to_ary || [object]
+      else
+        [object]
+      end
+    end
   end
 end

spec/cancan/ability_spec.rb

@@ -441,6 +441,31 @@ class Container < Hash
     expect(@ability.attributes_for(:new, Range)).to eq(foo: 'foo', bar: 123, baz: 'baz')
   end
 
+  it 'allows to check ability even the object implements `#to_a`' do
+    stub_const('X', Class.new do
+      def self.to_a
+        []
+      end
+    end)
+
+    @ability.can :read, X
+    expect(@ability.can?(:read, X.new)).to be(true)
+  end
+
+  it 'respects `#to_ary`' do
+    stub_const('X', Class.new do
+      def self.to_ary
+        [Y]
+      end
+    end)
+
+    stub_const('Y', Class.new)
+
+    @ability.can :read, X
+    expect(@ability.can?(:read, X.new)).to be(false)
+    expect(@ability.can?(:read, Y.new)).to be(true)
+  end
+
   # rubocop:disable Style/SymbolProc
   describe 'different usages of blocks and procs' do
     class A