3 files changed, 142 insertions, 12 deletions
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 57487cf75a..31516dc8a9 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -3,6 +3,7 @@ require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/hash/keys'
 require 'active_model/errors'
+require 'active_model/validations/callbacks'
 
 module ActiveModel
 
@@ -45,6 +46,7 @@ module ActiveModel
   module Validations
     extend ActiveSupport::Concern
     include ActiveSupport::Callbacks
+    include ActiveModel::Validations::Callbacks
 
     included do
       extend ActiveModel::Translation
@@ -158,18 +160,6 @@ module ActiveModel
       @errors ||= Errors.new(self)
     end
 
-    # Runs all the specified validations and returns true if no errors were added
-    # otherwise false. Context can optionally be supplied to define which callbacks
-    # to test against (the context is defined on the validations using :on).
-    def valid?(context = nil)
-      current_context, self.validation_context = validation_context, context
-      errors.clear
-      _run_validate_callbacks
-      errors.empty?
-    ensure
-      self.validation_context = current_context
-    end
-
     # Performs the opposite of <tt>valid?</tt>. Returns true if errors were added, 
     # false otherwise.
     def invalid?(context = nil)
diff --git a/activemodel/lib/active_model/validations/callbacks.rb b/activemodel/lib/active_model/validations/callbacks.rb
new file mode 100644
index 0000000000..2c8798bcdd
--- /dev/null
+++ b/activemodel/lib/active_model/validations/callbacks.rb
@@ -0,0 +1,64 @@
+require 'active_support/callbacks'
+
+module ActiveModel
+  module Validations
+    module Callbacks
+      # == Active Model Validation callbacks
+      #
+      # Provides an interface for any class to have <tt>before_validation</tt> and
+      # <tt>after_validation</tt> callbacks.
+      #
+      # First, extend ActiveModel::Callbacks from the class you are creating:
+      #
+      #   class MyModel
+      #     include ActiveModel::Validations::Callbacks
+      #
+      #     before_validation :do_stuff_before_validation
+      #     after_validation  :do_tuff_after_validation
+      #   end
+      #
+      #   Like other before_* callbacks if <tt>before_validation</tt> returns false
+      #   then <tt>valid?</tt> will not be called.
+      extend ActiveSupport::Concern
+
+      included do
+        include ActiveSupport::Callbacks
+        define_callbacks :validation, :terminator => "result == false", :scope => [:kind, :name]
+      end
+
+      module ClassMethods
+        def before_validation(*args, &block)
+          options = args.last
+          if options.is_a?(Hash) && options[:on]
+            options[:if] = Array.wrap(options[:if])
+            options[:if] << "self.validation_context == :#{options[:on]}"
+          end
+          set_callback(:validation, :before, *args, &block)
+        end
+
+        def after_validation(*args, &block)
+          options = args.extract_options!
+          options[:prepend] = true
+          options[:if] = Array.wrap(options[:if])
+          options[:if] << "!halted && value != false"
+          options[:if] << "self.validation_context == :#{options[:on]}" if options[:on]
+          set_callback(:validation, :after, *(args << options), &block)
+        end
+      end
+
+      # Runs all the specified validations and returns true if no errors were added
+      # otherwise false. Context can optionally be supplied to define which callbacks
+      # to test against (the context is defined on the validations using :on).
+      def valid?(context = nil)
+        current_context, self.validation_context = validation_context, context
+        errors.clear
+        @validate_callback_result = nil
+        validation_callback_result = _run_validation_callbacks { @validate_callback_result = _run_validate_callbacks }
+        (validation_callback_result && @validate_callback_result) ? errors.empty? : false
+      ensure
+        self.validation_context = current_context
+      end
+
+    end
+  end
+end
diff --git a/activemodel/test/cases/validations/callbacks_test.rb b/activemodel/test/cases/validations/callbacks_test.rb
new file mode 100644
index 0000000000..08dcf254c2
--- /dev/null
+++ b/activemodel/test/cases/validations/callbacks_test.rb
@@ -0,0 +1,76 @@
+# encoding: utf-8
+require 'cases/helper'
+
+class Dog
+  include ActiveModel::Validations
+
+  attr_accessor :name, :history
+
+  def history
+    @history ||= []
+  end
+end
+
+class DogWithMethodCallbacks < Dog
+  before_validation :set_before_validation_marker
+  after_validation :set_after_validation_marker
+
+  def set_before_validation_marker; self.history << 'before_validation_marker'; end
+  def set_after_validation_marker;  self.history << 'after_validation_marker' ; end
+end
+
+class DogValidtorsAreProc < Dog
+  before_validation { self.history << 'before_validation_marker' }
+  after_validation  { self.history << 'after_validation_marker' }
+end
+
+class DogWithTwoValidators < Dog
+  before_validation { self.history << 'before_validation_marker1' }
+  before_validation { self.history << 'before_validation_marker2' }
+end
+
+class DogValidatorReturningFalse < Dog
+  before_validation { false }
+  before_validation { self.history << 'before_validation_marker2' }
+end
+
+class DogWithMissingName < Dog
+  before_validation { self.history << 'before_validation_marker' }
+  validates_presence_of :name
+end
+
+class CallbacksWithMethodNamesShouldBeCalled < ActiveModel::TestCase
+
+  def test_before_validation_and_after_validation_callbacks_should_be_called
+    d = DogWithMethodCallbacks.new
+    d.valid?
+    assert_equal ['before_validation_marker', 'after_validation_marker'], d.history
+  end
+
+  def test_before_validation_and_after_validation_callbacks_should_be_called_with_proc
+    d = DogValidtorsAreProc.new
+    d.valid?
+    assert_equal ['before_validation_marker', 'after_validation_marker'], d.history
+  end
+
+  def test_before_validation_and_after_validation_callbacks_should_be_called_in_declared_order
+    d = DogWithTwoValidators.new
+    d.valid?
+    assert_equal ['before_validation_marker1', 'before_validation_marker2'], d.history
+  end
+
+  def test_further_callbacks_should_not_be_called_if_before_validation_returns_false
+    d = DogValidatorReturningFalse.new
+    output = d.valid?
+    assert_equal [], d.history
+    assert_equal false, output
+  end
+
+  def test_validation_test_should_be_done
+    d = DogWithMissingName.new
+    output = d.valid?
+    assert_equal ['before_validation_marker'], d.history
+    assert_equal false, output
+  end
+
+end