Make error_class work on inner wrapper

lib/simple_form/wrappers/many.rb

@@ -67,7 +67,9 @@ def html_options(options)
       end
 
       def html_classes(input, options)
-        @defaults[:class].dup
+        css = @defaults[:class].dup
+        css << @defaults[:error_class].dup { input.has_errors? }
+        css.compact
       end
     end
   end

test/form_builder/wrapper_test.rb

@@ -375,4 +375,11 @@ class WrapperTest < ActionView::TestCase
       assert_no_select 'p.omg_hint'
     end
   end
+
+  test 'inline wrapper has an error class' do
+    swap_wrapper :default, custom_wrapper_with_error_class do
+      with_form_for @user, :name
+      assert_select 'section.custom_wrapper div.custom_error'
+    end
+  end
 end

test/support/misc_helpers.rb

@@ -85,6 +85,14 @@ def custom_wrapper_with_unless_blank
     end
   end
 
+  def custom_wrapper_with_error_class
+    SimpleForm.build tag: :section, class: "custom_wrapper" do |b|
+      b.wrapper tag: :div, error_class: 'custom_error' do |ba|
+        ba.optional :hint, wrap_with: { tag: :p, class: 'omg_hint' }
+      end
+    end
+  end
+
   def custom_wrapper_with_input_class
     SimpleForm.build tag: :div, class: "custom_wrapper" do |b|
       b.use :label