Search for validations on both association and attribute (association_id) when testing for attribute required

lib/simple_form/inputs/base.rb

@@ -56,12 +56,20 @@ module SimpleForm
         if options.key?(:required)
           options[:required]
         elsif object.class.respond_to?(:validators_on)
-          object.class.validators_on(attribute_name).any? { |v| v.kind == :presence }
+          (attribute_validators + reflection_validators).any? { |v| v.kind == :presence }
         else
           attribute_required_by_default?
         end
       end
 
+      def attribute_validators
+        object.class.validators_on(attribute_name)
+      end
+
+      def reflection_validators
+        reflection ? object.class.validators_on(reflection.name) : []
+      end
+
       def attribute_required_by_default?
         SimpleForm.required_by_default
       end

test/form_builder_test.rb

@@ -429,6 +429,13 @@ class FormBuilderTest < ActionView::TestCase
     assert_equal 3, calls
   end
 
+  test 'builder association mark input as required based both association and attribute' do
+    swap SimpleForm, :required_by_default => false do
+      with_association_for @validating_user, :company, :collection => []
+      assert_select 'label.required'
+    end
+  end
+
   # ASSOCIATIONS - BELONGS TO
   test 'builder creates a select for belongs_to associations' do
     with_association_for @user, :company

test/support/models.rb

@@ -107,4 +107,5 @@ end
 class ValidatingUser < User
   include ActiveModel::Validations
   validates :name, :presence => true
+  validates :company, :presence => true
 end

test/test_helper.rb

@@ -59,7 +59,8 @@ class ActionView::TestCase
       :id => 1,
       :name => 'New in Simple Form!',
       :description => 'Hello!',
-      :created_at => Time.now
+      :created_at => Time.now,
+      :company => 1
     }.merge(options))
   end