Find all validators for multiple attributes

2 files changed, 22 insertions, 2 deletions

diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index cdf23c7b1b..a0f90452b3 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -146,8 +146,10 @@ module ActiveModel
       end
 
       # List all validators that being used to validate a specific attribute.
-      def validators_on(attribute)
-        _validators[attribute.to_sym]
+      def validators_on(*attributes)
+        attributes.inject([]) do |all, attribute|
+          all |= _validators[attribute.to_sym] || []
+        end
       end
 
       # Check if method is an attribute method or not.
diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index e90dc7d4e3..2f36195627 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -254,6 +254,24 @@ class ValidationsTest < ActiveModel::TestCase
     assert_equal 10, Topic.validators_on(:title).first.options[:minimum]
   end
 
+  def test_list_of_validators_on_multiple_attributes
+    Topic.validates :title, :length => { :minimum => 10 }
+    Topic.validates :author_name, :presence => true, :format => /a/
+
+    validators = Topic.validators_on(:title, :author_name)
+
+    assert_equal [
+      ActiveModel::Validations::FormatValidator,
+      ActiveModel::Validations::LengthValidator,
+      ActiveModel::Validations::PresenceValidator
+    ], validators.map { |v| v.class }.sort_by { |c| c.to_s }
+  end
+
+  def test_list_of_validators_will_be_empty_when_empty
+    Topic.validates :title, :length => { :minimum => 10 }
+    assert_equal [], Topic.validators_on(:author_name)
+  end
+
   def test_validations_on_the_instance_level
     auto = Automobile.new