Include ActiveModel::Validations from ActiveRecord::Validations

activerecord/lib/active_record/base.rb

@@ -3136,7 +3136,7 @@ def clone_attribute_value(reader_method, attribute_name)
 
   Base.class_eval do
     extend QueryCache::ClassMethods
-    include ::ActiveModel::Validations, Validations
+    include Validations
     include Locking::Optimistic, Locking::Pessimistic
     include AttributeMethods
     include Dirty

activerecord/lib/active_record/validations.rb

@@ -14,10 +14,16 @@ def initialize(record)
     end
   end
 
+  class Errors < ActiveModel::Errors
+  end
+
   module Validations
     def self.included(base) # :nodoc:
       base.extend ClassMethods
 
+      base.send :include, ActiveModel::Validations
+      base.send :include, InstanceMethods
+
       base.class_eval do
         alias_method_chain :save, :validation
         alias_method_chain :save!, :validation
@@ -38,31 +44,34 @@ def create!(attributes = nil, &block)
         end
       end
     end
-    
-    # The validation process on save can be skipped by passing false. The regular Base#save method is
-    # replaced with this when the validations module is mixed in, which it is by default.
-    def save_with_validation(perform_validation = true)
-      if perform_validation && valid? || !perform_validation
-        save_without_validation
-      else
-        false
+
+    module InstanceMethods
+      # The validation process on save can be skipped by passing false. The regular Base#save method is
+      # replaced with this when the validations module is mixed in, which it is by default.
+      def save_with_validation(perform_validation = true)
+        if perform_validation && valid? || !perform_validation
+          save_without_validation
+        else
+          false
+        end
+      end
+
+      # Attempts to save the record just like Base#save but will raise a RecordInvalid exception instead of returning false
+      # if the record is not valid.
+      def save_with_validation!
+        if valid?
+          save_without_validation!
+        else
+          raise RecordInvalid.new(self)
+        end
       end
-    end
 
-    # Attempts to save the record just like Base#save but will raise a RecordInvalid exception instead of returning false
-    # if the record is not valid.
-    def save_with_validation!
-      if valid?
-        save_without_validation!
-      else
-        raise RecordInvalid.new(self)
+      # Returns the Errors object that holds all information about attribute error messages.
+      def errors
+        @errors ||= Errors.new(self)
       end
     end
 
-    # Returns the Errors object that holds all information about attribute error messages.
-    def errors
-      @errors ||= Errors.new(self)
-    end
   end
 end