validate related records in the same validation context as parent.

E.G.:

```ruby
class Parent < ActiveRecord::Base
  has_one :child
  validates_presence_of :name, :on => "custom_context"
  validates_associated :child
end

class Child < ActiveRecord::Base
  belongs_to :parent
  validates_presence_of :name, :on => "custom_context"
end

p = Parent.new(:name => "Montoto", :child => Child.new)
p.valid?(:custom_context) # => Returns true, even though the child is not valid under the same context.
```

1 files changed, 17 insertions, 0 deletions

diff --git a/activerecord/test/cases/validations/association_validation_test.rb b/activerecord/test/cases/validations/association_validation_test.rb
index f155b9bc40..c72b7b35cd 100644
--- a/activerecord/test/cases/validations/association_validation_test.rb
+++ b/activerecord/test/cases/validations/association_validation_test.rb
@@ -118,4 +118,21 @@ class AssociationValidationTest < ActiveRecord::TestCase
     end
   end
 
+  def test_validates_associated_models_in_the_same_context
+    Topic.validates_presence_of :title, :on => :custom_context
+    Topic.validates_associated :replies
+    Reply.validates_presence_of :title, :on => :custom_context
+
+    t = Topic.new('title' => '')
+    r = t.replies.new('title' => '')
+
+    assert t.valid?
+    assert !t.valid?(:custom_context)
+
+    t.title = "Longer"
+    assert !t.valid?(:custom_context), "Should NOT be valid if the associated object is not valid in the same context."
+
+    r.title = "Longer"
+    assert t.valid?(:custom_context), "Should be valid if the associated object is not valid in the same context."
+  end
 end