diff --git a/activerecord/test/cases/helper.rb b/activerecord/test/cases/helper.rb
index afba715448..2043138ca3 100644
--- a/activerecord/test/cases/helper.rb
+++ b/activerecord/test/cases/helper.rb
@@ -9,6 +9,8 @@ require 'active_record/test_case'
 require 'active_record/fixtures'
 require 'connection'
 
+require 'cases/repair_helper'
+
 # Show backtraces for deprecated behavior for quicker cleanup.
 ActiveSupport::Deprecation.debug = true
 
@@ -60,6 +62,8 @@ end
 
 class ActiveSupport::TestCase
   include ActiveRecord::TestFixtures
+  include ActiveRecord::Testing::RepairHelper
+
   self.fixture_path = FIXTURES_ROOT
   self.use_instantiated_fixtures  = false
   self.use_transactional_fixtures = true
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index c049659327..380d8ac260 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -6,6 +6,8 @@ require 'models/person'
 require 'models/developer'
 require 'models/warehouse_thing'
 require 'models/guid'
+require 'models/owner'
+require 'models/pet'
 
 # The following methods in Topic are used in test_conditional_validation_*
 class Topic
@@ -31,10 +33,6 @@ class UniqueReply < Reply
   validates_uniqueness_of :content, :scope => 'parent_id'
 end
 
-class PlagiarizedReply < Reply
-  validates_acceptance_of :author_name
-end
-
 class SillyUniqueReply < UniqueReply
 end
 
@@ -58,11 +56,9 @@ end
 class ValidationsTest < ActiveRecord::TestCase
   fixtures :topics, :developers, 'warehouse-things'
 
-  def setup
-    Topic.instance_variable_set("@validate_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-    Topic.instance_variable_set("@validate_on_create_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-    Topic.instance_variable_set("@validate_on_update_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-  end
+  # Most of the tests mess with the validations of Topic, so lets repair it all the time.
+  # Other classes we mess with will be dealt with in the specific tests
+  repair_validations(Topic)
 
   def test_single_field_validation
     r = Reply.new
@@ -134,7 +130,7 @@ class ValidationsTest < ActiveRecord::TestCase
       Reply.create!([ { "title" => "OK" }, { "title" => "Wrong Create" }])
     end
   end
-  
+
   def test_exception_on_create_bang_with_block
     assert_raises(ActiveRecord::RecordInvalid) do
       Reply.create!({ "title" => "OK" }) do |r|
@@ -142,7 +138,7 @@ class ValidationsTest < ActiveRecord::TestCase
       end
     end
   end
-  
+
   def test_exception_on_create_bang_many_with_block
     assert_raises(ActiveRecord::RecordInvalid) do
       Reply.create!([{ "title" => "OK" }, { "title" => "Wrong Create" }]) do |r|
@@ -229,21 +225,16 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_each
-    perform = true
     hits = 0
     Topic.validates_each(:title, :content, [:title, :content]) do |record, attr|
-      if perform
-        record.errors.add attr, 'gotcha'
-        hits += 1
-      end
+      record.errors.add attr, 'gotcha'
+      hits += 1
     end
     t = Topic.new("title" => "valid", "content" => "whatever")
     assert !t.save
     assert_equal 4, hits
     assert_equal %w(gotcha gotcha), t.errors.on(:title)
     assert_equal %w(gotcha gotcha), t.errors.on(:content)
-  ensure
-    perform = false
   end
 
   def test_no_title_confirmation
@@ -315,8 +306,12 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_acceptance_of_as_database_column
-    reply = PlagiarizedReply.create("author_name" => "Dan Brown")
-    assert_equal "Dan Brown", reply["author_name"]
+    repair_validations(Reply) do
+      Reply.validates_acceptance_of(:author_name)
+
+      reply = Reply.create("author_name" => "Dan Brown")
+      assert_equal "Dan Brown", reply["author_name"]
+    end
   end
 
   def test_validates_acceptance_of_with_non_existant_table
@@ -372,22 +367,24 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validate_uniqueness_with_scope
-    Reply.validates_uniqueness_of(:content, :scope => "parent_id")
+    repair_validations(Reply) do
+      Reply.validates_uniqueness_of(:content, :scope => "parent_id")
 
-    t = Topic.create("title" => "I'm unique!")
+      t = Topic.create("title" => "I'm unique!")
 
-    r1 = t.replies.create "title" => "r1", "content" => "hello world"
-    assert r1.valid?, "Saving r1"
+      r1 = t.replies.create "title" => "r1", "content" => "hello world"
+      assert r1.valid?, "Saving r1"
 
-    r2 = t.replies.create "title" => "r2", "content" => "hello world"
-    assert !r2.valid?, "Saving r2 first time"
+      r2 = t.replies.create "title" => "r2", "content" => "hello world"
+      assert !r2.valid?, "Saving r2 first time"
 
-    r2.content = "something else"
-    assert r2.save, "Saving r2 second time"
+      r2.content = "something else"
+      assert r2.save, "Saving r2 second time"
 
-    t2 = Topic.create("title" => "I'm unique too!")
-    r3 = t2.replies.create "title" => "r3", "content" => "hello world"
-    assert r3.valid?, "Saving r3"
+      t2 = Topic.create("title" => "I'm unique too!")
+      r3 = t2.replies.create "title" => "r3", "content" => "hello world"
+      assert r3.valid?, "Saving r3"
+    end
   end
 
   def test_validate_uniqueness_scoped_to_defining_class
@@ -406,27 +403,29 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validate_uniqueness_with_scope_array
-    Reply.validates_uniqueness_of(:author_name, :scope => [:author_email_address, :parent_id])
+    repair_validations(Reply) do
+      Reply.validates_uniqueness_of(:author_name, :scope => [:author_email_address, :parent_id])
 
-    t = Topic.create("title" => "The earth is actually flat!")
+      t = Topic.create("title" => "The earth is actually flat!")
 
-    r1 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply"
-    assert r1.valid?, "Saving r1"
+      r1 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply"
+      assert r1.valid?, "Saving r1"
 
-    r2 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply again..."
-    assert !r2.valid?, "Saving r2. Double reply by same author."
+      r2 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply again..."
+      assert !r2.valid?, "Saving r2. Double reply by same author."
 
-    r2.author_email_address = "jeremy_alt_email@rubyonrails.com"
-    assert r2.save, "Saving r2 the second time."
+      r2.author_email_address = "jeremy_alt_email@rubyonrails.com"
+      assert r2.save, "Saving r2 the second time."
 
-    r3 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy_alt_email@rubyonrails.com", "title" => "You're wrong", "content" => "It's cubic"
-    assert !r3.valid?, "Saving r3"
+      r3 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy_alt_email@rubyonrails.com", "title" => "You're wrong", "content" => "It's cubic"
+      assert !r3.valid?, "Saving r3"
 
-    r3.author_name = "jj"
-    assert r3.save, "Saving r3 the second time."
+      r3.author_name = "jj"
+      assert r3.save, "Saving r3 the second time."
 
-    r3.author_name = "jeremy"
-    assert !r3.save, "Saving r3 the third time."
+      r3.author_name = "jeremy"
+      assert !r3.save, "Saving r3 the third time."
+    end
   end
 
   def test_validate_case_insensitive_uniqueness
@@ -523,10 +522,12 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validate_uniqueness_with_columns_which_are_sql_keywords
-    Guid.validates_uniqueness_of :key
-    g = Guid.new
-    g.key = "foo"
-    assert_nothing_raised { !g.valid? }
+    repair_validations(Guid) do
+      Guid.validates_uniqueness_of :key
+      g = Guid.new
+      g.key = "foo"
+      assert_nothing_raised { !g.valid? }
+    end
   end
 
   def test_validate_straight_inheritance_uniqueness
@@ -648,10 +649,12 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_numericality_with_getter_method
-    Developer.validates_numericality_of( :salary )
-    developer = Developer.new("name" => "michael", "salary" => nil)
-    developer.instance_eval("def salary; read_attribute('salary') ? read_attribute('salary') : 100000; end")
-    assert developer.valid?
+    repair_validations(Developer) do
+      Developer.validates_numericality_of( :salary )
+      developer = Developer.new("name" => "michael", "salary" => nil)
+      developer.instance_eval("def salary; read_attribute('salary') ? read_attribute('salary') : 100000; end")
+      assert developer.valid?
+    end
   end
 
   def test_validates_length_of_with_allow_nil
@@ -684,10 +687,12 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_numericality_with_allow_nil_and_getter_method
-    Developer.validates_numericality_of( :salary, :allow_nil => true)
-    developer = Developer.new("name" => "michael", "salary" => nil)
-    developer.instance_eval("def salary; read_attribute('salary') ? read_attribute('salary') : 100000; end")
-    assert developer.valid?
+    repair_validations(Developer) do
+      Developer.validates_numericality_of( :salary, :allow_nil => true)
+      developer = Developer.new("name" => "michael", "salary" => nil)
+      developer.instance_eval("def salary; read_attribute('salary') ? read_attribute('salary') : 100000; end")
+      assert developer.valid?
+    end
   end
 
   def test_validates_exclusion_of
@@ -892,26 +897,30 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_size_of_association
-    assert_nothing_raised { Topic.validates_size_of :replies, :minimum => 1 }
-    t = Topic.new('title' => 'noreplies', 'content' => 'whatever')
-    assert !t.save
-    assert t.errors.on(:replies)
-    reply = t.replies.build('title' => 'areply', 'content' => 'whateveragain')
-    assert t.valid?
+    repair_validations(Owner) do
+      assert_nothing_raised { Owner.validates_size_of :pets, :minimum => 1 }
+      o = Owner.new('name' => 'nopets')
+      assert !o.save
+      assert o.errors.on(:pets)
+      pet = o.pets.build('name' => 'apet')
+      assert o.valid?
+    end
   end
 
   def test_validates_size_of_association_using_within
-    assert_nothing_raised { Topic.validates_size_of :replies, :within => 1..2 }
-    t = Topic.new('title' => 'noreplies', 'content' => 'whatever')
-    assert !t.save
-    assert t.errors.on(:replies)
+    repair_validations(Owner) do
+      assert_nothing_raised { Owner.validates_size_of :pets, :within => 1..2 }
+      o = Owner.new('name' => 'nopets')
+      assert !o.save
+      assert o.errors.on(:pets)
 
-    reply = t.replies.build('title' => 'areply', 'content' => 'whateveragain')
-    assert t.valid?
+      pet = o.pets.build('name' => 'apet')
+      assert o.valid?
 
-    2.times { t.replies.build('title' => 'areply', 'content' => 'whateveragain') }
-    assert !t.save
-    assert t.errors.on(:replies)
+      2.times { o.pets.build('name' => 'apet') }
+      assert !o.save
+      assert o.errors.on(:pets)
+    end
   end
 
   def test_validates_length_of_nasty_params
@@ -1102,13 +1111,15 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_size_of_association_utf8
-    with_kcode('UTF8') do
-      assert_nothing_raised { Topic.validates_size_of :replies, :minimum => 1 }
-      t = Topic.new('title' => 'あいうえお', 'content' => 'かきくけこ')
-      assert !t.save
-      assert t.errors.on(:replies)
-      t.replies.build('title' => 'あいうえお', 'content' => 'かきくけこ')
-      assert t.valid?
+    repair_validations(Owner) do
+      with_kcode('UTF8') do
+        assert_nothing_raised { Owner.validates_size_of :pets, :minimum => 1 }
+        o = Owner.new('name' => 'あいうえおかきくけこ')
+        assert !o.save
+        assert o.errors.on(:pets)
+        o.pets.build('name' => 'あいうえおかきくけこ')
+        assert o.valid?
+      end
     end
   end
 
@@ -1127,14 +1138,16 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_associated_one
-    Reply.validates_associated( :topic )
-    Topic.validates_presence_of( :content )
-    r = Reply.new("title" => "A reply", "content" => "with content!")
-    r.topic = Topic.create("title" => "uhohuhoh")
-    assert !r.valid?
-    assert r.errors.on(:topic)
-    r.topic.content = "non-empty"
-    assert r.valid?
+    repair_validations(Reply) do
+      Reply.validates_associated( :topic )
+      Topic.validates_presence_of( :content )
+      r = Reply.new("title" => "A reply", "content" => "with content!")
+      r.topic = Topic.create("title" => "uhohuhoh")
+      assert !r.valid?
+      assert r.errors.on(:topic)
+      r.topic.content = "non-empty"
+      assert r.valid?
+    end
   end
 
   def test_validate_block
@@ -1158,85 +1171,105 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_acceptance_of_with_custom_error_using_quotes
-    Developer.validates_acceptance_of :salary, :message=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.salary = "0"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:salary).last
+    repair_validations(Developer) do
+      Developer.validates_acceptance_of :salary, :message=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.salary = "0"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:salary).last
+    end
   end
 
   def test_validates_confirmation_of_with_custom_error_using_quotes
-    Developer.validates_confirmation_of :name, :message=> "confirm 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "John"
-    d.name_confirmation = "Johnny"
-    assert !d.valid?
-    assert_equal "confirm 'single' and \"double\" quotes", d.errors.on(:name)
+    repair_validations(Developer) do
+      Developer.validates_confirmation_of :name, :message=> "confirm 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "John"
+      d.name_confirmation = "Johnny"
+      assert !d.valid?
+      assert_equal "confirm 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_format_of_with_custom_error_using_quotes
-    Developer.validates_format_of :name, :with => /^(A-Z*)$/, :message=> "format 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = d.name_confirmation = "John 32"
-    assert !d.valid?
-    assert_equal "format 'single' and \"double\" quotes", d.errors.on(:name)
+    repair_validations(Developer) do
+      Developer.validates_format_of :name, :with => /^(A-Z*)$/, :message=> "format 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = d.name_confirmation = "John 32"
+      assert !d.valid?
+      assert_equal "format 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_inclusion_of_with_custom_error_using_quotes
-    Developer.validates_inclusion_of :salary, :in => 1000..80000, :message=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.salary = "90,000"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:salary).last
+    repair_validations(Developer) do
+      Developer.validates_inclusion_of :salary, :in => 1000..80000, :message=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.salary = "90,000"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:salary).last
+    end
   end
 
   def test_validates_length_of_with_custom_too_long_using_quotes
-    Developer.validates_length_of :name, :maximum => 4, :too_long=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "Jeffrey"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name).last
+    repair_validations(Developer) do
+      Developer.validates_length_of :name, :maximum => 4, :too_long=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "Jeffrey"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_length_of_with_custom_too_short_using_quotes
-    Developer.validates_length_of :name, :minimum => 4, :too_short=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "Joe"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name).last
+    repair_validations(Developer) do
+      Developer.validates_length_of :name, :minimum => 4, :too_short=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "Joe"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_length_of_with_custom_message_using_quotes
-    Developer.validates_length_of :name, :minimum => 4, :message=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "Joe"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name).last
+    repair_validations(Developer) do
+      Developer.validates_length_of :name, :minimum => 4, :message=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "Joe"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_presence_of_with_custom_message_using_quotes
-    Developer.validates_presence_of :non_existent, :message=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "Joe"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:non_existent)
+    repair_validations(Developer) do
+      Developer.validates_presence_of :non_existent, :message=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "Joe"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:non_existent)
+    end
   end
 
   def test_validates_uniqueness_of_with_custom_message_using_quotes
-    Developer.validates_uniqueness_of :name, :message=> "This string contains 'single' and \"double\" quotes"
-    d = Developer.new
-    d.name = "David"
-    assert !d.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name).last
+    repair_validations(Developer) do
+      Developer.validates_uniqueness_of :name, :message=> "This string contains 'single' and \"double\" quotes"
+      d = Developer.new
+      d.name = "David"
+      assert !d.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", d.errors.on(:name)
+    end
   end
 
   def test_validates_associated_with_custom_message_using_quotes
-    Reply.validates_associated :topic, :message=> "This string contains 'single' and \"double\" quotes"
-    Topic.validates_presence_of :content
-    r = Reply.create("title" => "A reply", "content" => "with content!")
-    r.topic = Topic.create("title" => "uhohuhoh")
-    assert !r.valid?
-    assert_equal "This string contains 'single' and \"double\" quotes", r.errors.on(:topic).last
+    repair_validations(Reply) do
+      Reply.validates_associated :topic, :message=> "This string contains 'single' and \"double\" quotes"
+      Topic.validates_presence_of :content
+      r = Reply.create("title" => "A reply", "content" => "with content!")
+      r.topic = Topic.create("title" => "uhohuhoh")
+      assert !r.valid?
+      assert_equal "This string contains 'single' and \"double\" quotes", r.errors.on(:topic)
+    end
   end
 
   def test_if_validation_using_method_true
@@ -1346,13 +1379,15 @@ class ValidationsTest < ActiveRecord::TestCase
   end
 
   def test_validates_associated_missing
-    Reply.validates_presence_of(:topic)
-    r = Reply.create("title" => "A reply", "content" => "with content!")
-    assert !r.valid?
-    assert r.errors.on(:topic)
+    repair_validations(Reply) do
+      Reply.validates_presence_of(:topic)
+      r = Reply.create("title" => "A reply", "content" => "with content!")
+      assert !r.valid?
+      assert r.errors.on(:topic)
 
-    r.topic = Topic.find :first
-    assert r.valid?
+      r.topic = Topic.find :first
+      assert r.valid?
+    end
   end
 
   def test_errors_to_xml
@@ -1364,14 +1399,14 @@ class ValidationsTest < ActiveRecord::TestCase
     assert xml.include?("<error>Content Empty</error>")
   end
 
- def test_validation_order
-    Topic.validates_presence_of :title
-    Topic.validates_length_of :title, :minimum => 2
+  def test_validation_order
+     Topic.validates_presence_of :title
+     Topic.validates_length_of :title, :minimum => 2
 
-    t = Topic.new("title" => "")
-    assert !t.valid?
-    assert_equal "can't be blank", t.errors.on("title").first
- end
+     t = Topic.new("title" => "")
+     assert !t.valid?
+     assert_equal "can't be blank", t.errors.on("title").first
+  end
 
   # previous implementation of validates_presence_of eval'd the
   # string with the wrong binding, this regression test is to
@@ -1423,11 +1458,7 @@ class ValidatesNumericalityTest < ActiveRecord::TestCase
   JUNK = ["not a number", "42 not a number", "0xdeadbeef", "00-1", "--3", "+-3", "+3-1", "-+019.0", "12.12.13.12", "123\nnot a number"]
   INFINITY = [1.0/0.0]
 
-  def setup
-    Topic.instance_variable_set("@validate_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-    Topic.instance_variable_set("@validate_on_create_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-    Topic.instance_variable_set("@validate_on_update_callbacks", ActiveSupport::Callbacks::CallbackChain.new)
-  end
+  repair_validations(Topic)
 
   def test_default_validates_numericality_of
     Topic.validates_numericality_of :approved