From 5b09d87f4850e6d16484c43c7af6e9c755abb471 Mon Sep 17 00:00:00 2001
From: Murray Steele <muz@h-lame.com>
Date: Thu, 17 Dec 2009 16:07:32 +0000
Subject: [PATCH] Make polymorphic_inverse_of in Reflection throw an InverseOfAssociationNotFoundError if the supplied class doesn't have the appropriate association.

---
 activerecord/lib/active_record/associations.rb     |    4 ++--
 activerecord/lib/active_record/reflection.rb       |    7 ++++++-
 .../associations/inverse_associations_test.rb      |   17 +++++++++++++++--
 activerecord/test/models/face.rb                   |    3 ++-
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 8dcb3a7..a41dcf3 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/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
 
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 72f7df3..f599a72 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -246,7 +246,12 @@ module ActiveRecord
 
       def polymorphic_inverse_of(associated_class)
         if has_inverse?
-          associated_class.reflect_on_association(options[:inverse_of])
+          inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
+          if inverse_relationship
+            inverse_relationship
+          else
+            raise InverseOfAssociationNotFoundError.new(self, associated_class)
+          end
         else
           nil
         end
diff --git a/activerecord/test/cases/associations/inverse_associations_test.rb b/activerecord/test/cases/associations/inverse_associations_test.rb
index 5ca3360..0f8420f 100644
--- a/activerecord/test/cases/associations/inverse_associations_test.rb
+++ b/activerecord/test/cases/associations/inverse_associations_test.rb
@@ -526,8 +526,21 @@ 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
 
diff --git a/activerecord/test/models/face.rb b/activerecord/test/models/face.rb
index 3e2bdc0..edb75d3 100644
--- a/activerecord/test/models/face.rb
+++ b/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
-- 
1.6.5.3