Make polymorphic_inverse_of in Reflection throw an InverseOfAssociationNotFoundError if the supplied class doesn't have the appropriate association. [#3520 state:resolved]

Signed-off-by: Eloy Duran <eloy.de.enige@gmail.com>

activerecord/lib/active_record/associations.rb

@@ -3,8 +3,8 @@ require 'active_support/core_ext/enumerable'
 
 module ActiveRecord
   class InverseOfAssociationNotFoundError < ActiveRecordError #:nodoc:
-    def initialize(reflection)
-      super("Could not find the inverse association for #{reflection.name} (#{reflection.options[:inverse_of].inspect} in #{reflection.class_name})")
+    def initialize(reflection, associated_class = nil)
+      super("Could not find the inverse association for #{reflection.name} (#{reflection.options[:inverse_of].inspect} in #{associated_class.nil? ? reflection.class_name : associated_class.name})")
     end
   end
 

activerecord/lib/active_record/reflection.rb

@@ -239,16 +239,16 @@ module ActiveRecord
       def inverse_of
         if has_inverse?
           @inverse_of ||= klass.reflect_on_association(options[:inverse_of])
-        else
-          nil
         end
       end
 
       def polymorphic_inverse_of(associated_class)
         if has_inverse?
-          associated_class.reflect_on_association(options[:inverse_of])
-        else
-          nil
+          if inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
+            inverse_relationship
+          else
+            raise InverseOfAssociationNotFoundError.new(self, associated_class)
+          end
         end
       end
 

activerecord/test/cases/associations/inverse_associations_test.rb

@@ -524,8 +524,21 @@ class InversePolymorphicBelongsToTests < ActiveRecord::TestCase
     assert_not_equal i.topic, iz.topic, "Interest topics should not be the same after changes to parent-owned instance"
   end
 
-  def test_trying_to_use_inverses_that_dont_exist_should_raise_an_error
-    assert_raise(ActiveRecord::InverseOfAssociationNotFoundError) { Face.find(:first).horrible_man }
+  def test_trying_to_access_inverses_that_dont_exist_shouldnt_raise_an_error
+    # Ideally this would, if only for symmetry's sake with other association types
+    assert_nothing_raised(ActiveRecord::InverseOfAssociationNotFoundError) { Face.find(:first).horrible_polymorphic_man }
+  end
+
+  def test_trying_to_set_polymorphic_inverses_that_dont_exist_at_all_should_raise_an_error
+    # fails because no class has the correct inverse_of for horrible_polymorphic_man
+    assert_raise(ActiveRecord::InverseOfAssociationNotFoundError) { Face.find(:first).horrible_polymorphic_man = Man.first }
+  end
+
+  def test_trying_to_set_polymorphic_inverses_that_dont_exist_on_the_instance_being_set_should_raise_an_error
+    # passes because Man does have the correct inverse_of
+    assert_nothing_raised(ActiveRecord::InverseOfAssociationNotFoundError) { Face.find(:first).polymorphic_man = Man.first }
+    # fails because Interest does have the correct inverse_of
+    assert_raise(ActiveRecord::InverseOfAssociationNotFoundError) { Face.find(:first).polymorphic_man = Interest.first }
   end
 end
 

activerecord/test/models/face.rb

@@ -1,6 +1,7 @@
 class Face < ActiveRecord::Base
   belongs_to :man, :inverse_of => :face
   belongs_to :polymorphic_man, :polymorphic => true, :inverse_of => :polymorphic_face
-  # This is a "broken" inverse_of for the purposes of testing
+  # These is a "broken" inverse_of for the purposes of testing
   belongs_to :horrible_man, :class_name => 'Man', :inverse_of => :horrible_face
+  belongs_to :horrible_polymorphic_man, :polymorphic => true, :inverse_of => :horrible_polymorphic_face
 end