Add required html attribute for inputs - HTML5, closes #63.

This also ensures hidden inputs does not have required/optional options.

lib/simple_form/inputs/base.rb

@@ -30,7 +30,9 @@ module SimpleForm
       end
 
       def input_html_options
-        html_options_for(:input, input_html_classes)
+        html_options = html_options_for(:input, input_html_classes)
+        html_options[:required] = true if attribute_required?
+        html_options
       end
 
       def input_html_classes

lib/simple_form/inputs/hidden_input.rb

@@ -5,6 +5,16 @@ module SimpleForm
         @builder.hidden_field(attribute_name, input_html_options)
       end
       alias :input :render
+
+    protected
+
+      def attribute_required?
+        false
+      end
+
+      def required_class
+        nil
+      end
     end
   end
 end

test/form_builder_test.rb

@@ -247,7 +247,7 @@ class FormBuilderTest < ActionView::TestCase
   # REQUIRED AND PRESENCE VALIDATION
   test 'builder input should obtain required from ActiveModel::Validations when it is included' do
     with_form_for @validating_user, :name
-    assert_select 'input.required#validating_user_name'
+    assert_select 'input.required[required]#validating_user_name'
     with_form_for @validating_user, :status
     assert_select 'input.optional#validating_user_status'
   end
@@ -256,24 +256,26 @@ class FormBuilderTest < ActionView::TestCase
     with_form_for @validating_user, :name, :required => false
     assert_select 'input.optional#validating_user_name'
     with_form_for @validating_user, :status, :required => true
-    assert_select 'input.required#validating_user_status'
+    assert_select 'input.required[required]#validating_user_status'
   end
 
   test 'builder input should be required by default when ActiveModel::Validations is not included' do
     with_form_for @user, :name
-    assert_select 'input.required#user_name'
+    assert_select 'input.required[required]#user_name'
   end
 
   test 'builder input should not be required by default when ActiveModel::Validations is not included if option is set to false' do
     swap SimpleForm, :required_by_default => false do
       with_form_for @user, :name
       assert_select 'input.optional#user_name'
+      assert_no_select 'input[required]'
     end
   end
 
   test 'builder input should allow disabling required when ActiveModel::Validations is not included' do
     with_form_for @user, :name, :required => false
     assert_no_select 'input.required'
+    assert_no_select 'input[required]'
     assert_select 'input.optional#user_name'
   end
 

test/inputs_test.rb

@@ -184,6 +184,14 @@ class InputTest < ActionView::TestCase
     assert_no_select 'label'
   end
 
+  test 'required/optional options should not be generated for hidden inputs' do
+    with_input_for @user, :name, :hidden
+    assert_no_select 'input.required'
+    assert_no_select 'input[required]'
+    assert_no_select 'input.optional'
+    assert_select 'input.hidden#user_name'
+  end
+
   # PriorityInput
   test 'input should generate a country select field' do
     with_input_for @user, :country, :country