Fix bug when simple_fields_for is used with a hask like model and imp…

…rove coverage.

Thanks to https://github.com/spohlenz for figuring this out in the Rails code.
See more: rails/rails#1778

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    simple_form (1.4.1)
+    simple_form (1.4.3.dev)
       actionpack (~> 3.0)
       activemodel (~> 3.0)
 
@@ -43,7 +43,7 @@ GEM
       ruby-debug-base (~> 0.10.4.0)
     ruby-debug-base (0.10.4)
       linecache (>= 0.3)
-    tzinfo (0.3.28)
+    tzinfo (0.3.29)
 
 PLATFORMS
   ruby

lib/simple_form/action_view_extensions/form_helper.rb

@@ -48,7 +48,7 @@ def simple_form_for(record, options={}, &block)
       end
 
       def simple_fields_for(record_name, record_object = nil, options = {}, &block)
-        options, record_object = record_object, nil if record_object.is_a?(Hash)
+        options, record_object = record_object, nil if record_object.is_a?(Hash) && record_object.extractable_options?
         options[:builder] ||= SimpleForm::FormBuilder
 
         with_custom_field_error_proc do

lib/simple_form/version.rb

@@ -1,3 +1,3 @@
 module SimpleForm
-  VERSION = "1.4.2".freeze
+  VERSION = "1.4.3.dev".freeze
 end

test/action_view_extensions/builder_test.rb

@@ -290,6 +290,19 @@ def with_collection_check_boxes(object, attribute, collection, value_method, tex
     end
   end
 
+  test 'fields for with a hash like model yeilds an instance of FormBuilder' do
+    @hash_backed_author = HashBackedAuthor.new
+
+    with_concat_form_for(:user) do |f|
+      f.simple_fields_for(:author, @hash_backed_author) do |author|
+        assert author.instance_of?(SimpleForm::FormBuilder)
+        author.input :name
+      end
+    end
+
+    assert_select "input[name='user[author][name]'][value='hash backed author']"
+  end
+
   test 'fields for yields an instance of CustomBuilder if main builder is a CustomBuilder' do
     with_custom_form_for(:user) do |f|
       f.simple_fields_for(:company) do |company|

test/action_view_extensions/form_helper_test.rb

@@ -58,4 +58,15 @@ class FormHelperTest < ActionView::TestCase
       assert f.instance_of?(SimpleForm::FormBuilder)
     end)
   end
+
+  test 'fields for with a hash like model yeilds an instance of FormBuilder' do
+    @hash_backed_author = HashBackedAuthor.new
+
+    concat(simple_fields_for(:author, @hash_backed_author) do |f|
+      assert f.instance_of?(SimpleForm::FormBuilder)
+      f.input :name
+    end)
+
+    assert_select "input[name='author[name]'][value='hash backed author']"
+  end
 end

test/support/models.rb

@@ -174,3 +174,14 @@ class OtherValidatingUser < User
     :less_than_or_equal_to => Proc.new { |user| user.age + 100},
     :only_integer => true
 end
+
+class HashBackedAuthor < Hash
+  extend ActiveModel::Naming
+  include ActiveModel::Conversion
+
+  def persisted?; false; end
+
+  def name
+    'hash backed author'
+  end
+end