Drop support for actions without a subject

CHANGELOG.rdoc

@@ -1,5 +1,7 @@
 Unreleased
 
+* Drop support for actions without a subject (andrew-aladev)
+
 * Removed support for dynamic finders (coorasse)
 
 2.1.3 (Jan 16th, 2018)

lib/cancan/exceptions.rb

@@ -11,6 +11,9 @@ class ImplementationRemoved < Error; end
   # Raised when using check_authorization without calling authorized!
   class AuthorizationNotPerformed < Error; end
 
+  # Raised when a rule is created with both a block and a hash of conditions
+  class BlockAndConditionsError < Error; end
+
   # This error is raised when a user isn't allowed to access a given controller action.
   # This usually happens within a call to ControllerAdditions#authorize! but can be
   # raised manually.

lib/cancan/rule.rb

@@ -13,10 +13,9 @@ class Rule # :nodoc:
     # and subject respectively (such as :read, @project). The third argument is a hash
     # of conditions and the last one is the block passed to the "can" call.
     def initialize(base_behavior, action, subject, conditions, block)
-      both_block_and_hash_error = 'You are not able to supply a block with a hash of conditions in '\
-                                  "#{action} #{subject} ability. Use either one."
-      raise Error, both_block_and_hash_error if conditions.is_a?(Hash) && block
+      condition_and_block_check(conditions, block, action, subject)
       @match_all = action.nil? && subject.nil?
+      raise Error, "Subject is required for #{action}" if action && subject.nil?
       @base_behavior = base_behavior
       @actions = Array(action)
       @subjects = Array(subject)
@@ -80,5 +79,11 @@ def matches_subject_class?(subject)
           (subject.is_a?(Module) && subject.ancestors.include?(sub)))
       end
     end
+
+    def condition_and_block_check(conditions, block, action, subject)
+      return unless conditions.is_a?(Hash) && block
+      raise BlockAndConditionsError, 'A hash of conditions is mutually exclusive with a block. '\
+              "Check \":#{action} #{subject}\" ability."
+    end
   end
 end

spec/cancan/ability_spec.rb

@@ -483,9 +483,15 @@ class Container < Hash
       @ability.can :read, Array, published: true do
         false
       end
-    end.to raise_error(CanCan::Error,
-                       'You are not able to supply a block with a hash of conditions in read Array ability. '\
-                       'Use either one.')
+    end.to raise_error(CanCan::BlockAndConditionsError,
+                       'A hash of conditions is mutually exclusive with a block. '\
+                       'Check ":read Array" ability.')
+  end
+
+  it 'raises an error when attempting to use action without subject' do
+    expect do
+      @ability.can :dashboard
+    end.to raise_error(CanCan::Error, 'Subject is required for dashboard')
   end
 
   describe 'unauthorized message' do