set the configured #inheritance_column on #become (#7503)

I had to create a new table because I needed an STI table,
which does not have both a "type" and a "custom_type"

the test fails with:
  1) Error:
test_alt_becomes_works_with_sti(InheritanceTest):
NoMethodError: undefined method `type=' for #<Cabbage id: 1, name: "my cucumber", custom_type: "Cucumber">
    /Users/username/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:432:in `method_missing'
    /Users/username/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:100:in `method_missing'
    /Users/username/Projects/rails/activerecord/lib/active_record/persistence.rb:165:in `becomes'
    test/cases/inheritance_test.rb:134:in `test_becomes_works_with_sti'
    test/cases/inheritance_test.rb:140:in `test_alt_becomes_works_with_sti'

Conflicts:

	activerecord/test/cases/inheritance_test.rb

6 files changed, 42 insertions, 2 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 3c1a400cc6..c836886c08 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,5 +1,9 @@
 ## Rails 3.2.9 (unreleased)
 
+*   Fix `becomes` when using a configured `inheritance_column`.
+
+    *Yves Senn*
+
 *   Fix `reset_counters` when there are multiple `belongs_to` association with the
     same foreign key and one of them have a counter cache.
     Fixes #5200.
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 038355deaa..8a3c3fed7d 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -162,7 +162,7 @@ module ActiveRecord
       became.instance_variable_set("@new_record", new_record?)
       became.instance_variable_set("@destroyed", destroyed?)
       became.instance_variable_set("@errors", errors)
-      became.type = klass.name unless self.class.descends_from_active_record?
+      became.send("#{klass.inheritance_column}=", klass.name) unless self.class.descends_from_active_record?
       became
     end
 
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index fab858e09c..54c9152c06 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -2,9 +2,10 @@ require "cases/helper"
 require 'models/company'
 require 'models/project'
 require 'models/subscriber'
+require 'models/vegetables'
 
 class InheritanceTest < ActiveRecord::TestCase
-  fixtures :companies, :projects, :subscribers, :accounts
+  fixtures :companies, :projects, :subscribers, :accounts, :vegetables
 
   def test_class_with_store_full_sti_class_returns_full_name
     old = ActiveRecord::Base.store_full_sti_class
@@ -98,6 +99,13 @@ class InheritanceTest < ActiveRecord::TestCase
     switch_to_default_inheritance_column
   end
 
+  def test_alt_becomes_works_with_sti
+    vegetable = Vegetable.find(1)
+    assert_kind_of Vegetable, vegetable
+    cabbage = vegetable.becomes(Cabbage)
+    assert_kind_of Cabbage, cabbage
+  end
+
   def test_inheritance_find_all
     companies = Company.find(:all, :order => 'id')
     assert_kind_of Firm, companies[0], "37signals should be a firm"
diff --git a/activerecord/test/fixtures/vegetables.yml b/activerecord/test/fixtures/vegetables.yml
new file mode 100644
index 0000000000..82bd607701
--- /dev/null
+++ b/activerecord/test/fixtures/vegetables.yml
@@ -0,0 +1,9 @@
+first_cucumber:
+  id: 1
+  custom_type: Cucumber
+  name: 'my cucumber'
+
+first_cabbage:
+  id: 2
+  custom_type: Cabbage
+  name: 'my cabbage'
\ No newline at end of file
diff --git a/activerecord/test/models/vegetables.rb b/activerecord/test/models/vegetables.rb
new file mode 100644
index 0000000000..59cedfd9f5
--- /dev/null
+++ b/activerecord/test/models/vegetables.rb
@@ -0,0 +1,14 @@
+class Vegetable < ActiveRecord::Base
+
+  validates_presence_of :name
+
+  def self.inheritance_column
+    'custom_type'
+  end
+end
+
+class Cucumber < Vegetable
+end
+
+class Cabbage < Vegetable
+end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index b3ae2abbc4..b8150c50b9 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -179,6 +179,11 @@ ActiveRecord::Schema.define do
 
   add_index :companies, [:firm_id, :type, :rating, :ruby_type], :name => "company_index"
 
+  create_table :vegetables, :force => true do |t|
+    t.string :name
+    t.string :custom_type
+  end
+
   create_table :computers, :force => true do |t|
     t.integer :developer, :null => false
     t.integer :extendedWarranty, :null => false