has_one :dependent => :nullify ignores nil associates. Closes #6528.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5401 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* has_one :dependent => :nullify ignores nil associates.  #6528 [janovetz, Jeremy Kemper]
+
 * Oracle: resolve test failures, use prefetched primary key for inserts, check for null defaults. Factor out some common methods from all adapters.  #6515 [Michael Schoen]
 
 * Make add_column use the options hash with the Sqlite Adapter. Closes #6464 [obrie]

activerecord/lib/active_record/associations.rb

@@ -1060,7 +1060,7 @@ def configure_dependency_for_has_one(reflection)
             when :delete
               module_eval "before_destroy '#{reflection.class_name}.delete(#{reflection.name}.id) unless #{reflection.name}.nil?'"
             when :nullify
-              module_eval "before_destroy '#{reflection.name}.update_attribute(\"#{reflection.primary_key_name}\", nil)'"
+              module_eval "before_destroy '#{reflection.name}.update_attribute(\"#{reflection.primary_key_name}\", nil) unless #{reflection.name}.nil?'"
             when nil, false
               # pass
             else

activerecord/test/associations_test.rb

@@ -184,11 +184,13 @@ def test_assignment_without_replacement_on_create
 
   def test_dependence
     num_accounts = Account.count
+
     firm = Firm.find(1)
     assert !firm.account.nil?
     account_id = firm.account.id
     assert_equal [], Account.destroyed_account_ids[firm.id]
-    firm.destroy                
+
+    firm.destroy
     assert_equal num_accounts - 1, Account.count
     assert_equal [account_id], Account.destroyed_account_ids[firm.id]
   end
@@ -201,15 +203,23 @@ def test_deprecated_exclusive_dependence
 
   def test_exclusive_dependence
     num_accounts = Account.count
+
     firm = ExclusivelyDependentFirm.find(9)
     assert !firm.account.nil?
     account_id = firm.account.id
     assert_equal [], Account.destroyed_account_ids[firm.id]
+
     firm.destroy
     assert_equal num_accounts - 1, Account.count
     assert_equal [], Account.destroyed_account_ids[firm.id]
   end
 
+  def test_dependence_with_nil_associate
+    firm = DependentFirm.new(:name => 'nullify')
+    firm.save!
+    assert_nothing_raised { firm.destroy }
+  end
+
   def test_succesful_build_association
     firm = Firm.new("name" => "GlobalMegaCorp")
     firm.save