Capture block so content won't leak.

The [following pull request](https://github.com/rails/rails/pull/8916) fixed
the block being passed to the appropriate helper method. However, the content
being passed into the block is generating repeated markup on the page due to
some weird ERb evaluation.

This commit tries to capture the block's generated output so the page isn't
flooded with markup.

[Rafael França + José Mota]

Closes #8936

3 files changed, 61 insertions, 4 deletions

diff --git a/actionpack/lib/action_view/helpers/tags/collection_check_boxes.rb b/actionpack/lib/action_view/helpers/tags/collection_check_boxes.rb
index d27df45b5a..9655008fe2 100644
--- a/actionpack/lib/action_view/helpers/tags/collection_check_boxes.rb
+++ b/actionpack/lib/action_view/helpers/tags/collection_check_boxes.rb
@@ -13,13 +13,13 @@ module ActionView
           end
         end
 
-        def render
+        def render(&block)
           rendered_collection = render_collection do |item, value, text, default_html_options|
             default_html_options[:multiple] = true
             builder = instantiate_builder(CheckBoxBuilder, item, value, text, default_html_options)
 
             if block_given?
-              yield builder
+              @template_object.capture(builder, &block)
             else
               render_component(builder)
             end
diff --git a/actionpack/lib/action_view/helpers/tags/collection_radio_buttons.rb b/actionpack/lib/action_view/helpers/tags/collection_radio_buttons.rb
index 81f2ecb2b3..893f4411e7 100644
--- a/actionpack/lib/action_view/helpers/tags/collection_radio_buttons.rb
+++ b/actionpack/lib/action_view/helpers/tags/collection_radio_buttons.rb
@@ -13,12 +13,12 @@ module ActionView
           end
         end
 
-        def render
+        def render(&block)
           render_collection do |item, value, text, default_html_options|
             builder = instantiate_builder(RadioButtonBuilder, item, value, text, default_html_options)
 
             if block_given?
-              yield builder
+              @template_object.capture(builder, &block)
             else
               render_component(builder)
             end
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index f9890a2eef..6892409081 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -1142,6 +1142,32 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_for_with_collection_radio_buttons_with_custom_builder_block_does_not_leak_the_template
+    post = Post.new
+    def post.active; false; end
+    def post.id; 1; end
+
+    form_for(post) do |f|
+      rendered_radio_buttons = f.collection_radio_buttons(:active, [true, false], :to_s, :to_s) do |b|
+        b.label { b.radio_button + b.text }
+      end
+      concat rendered_radio_buttons
+      concat f.hidden_field :id
+    end
+
+    expected = whole_form("/posts", "new_post_1", "new_post") do
+      "<label for='post_active_true'>"+
+      "<input id='post_active_true' name='post[active]' type='radio' value='true' />" +
+      "true</label>" +
+      "<label for='post_active_false'>"+
+      "<input checked='checked' id='post_active_false' name='post[active]' type='radio' value='false' />" +
+      "false</label>"+
+      "<input id='post_id' name='post[id]' type='hidden' value='1' />"
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
   def test_form_for_with_collection_check_boxes
     post = Post.new
     def post.tag_ids; [1, 3]; end
@@ -1190,6 +1216,37 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_for_with_collection_check_boxes_with_custom_builder_block_does_not_leak_the_template
+    post = Post.new
+    def post.tag_ids; [1, 3]; end
+    def post.id; 1; end
+    collection = (1..3).map{|i| [i, "Tag #{i}"] }
+
+    form_for(post) do |f|
+      rendered_check_boxes = f.collection_check_boxes(:tag_ids, collection, :first, :last) do |b|
+        b.label { b.check_box + b.text }
+      end
+      concat rendered_check_boxes
+      concat f.hidden_field :id
+    end
+
+    expected = whole_form("/posts", "new_post_1", "new_post") do
+      "<label for='post_tag_ids_1'>" +
+      "<input checked='checked' id='post_tag_ids_1' name='post[tag_ids][]' type='checkbox' value='1' />" +
+      "Tag 1</label>" +
+      "<label for='post_tag_ids_2'>" +
+      "<input id='post_tag_ids_2' name='post[tag_ids][]' type='checkbox' value='2' />" +
+      "Tag 2</label>" +
+      "<label for='post_tag_ids_3'>" +
+      "<input checked='checked' id='post_tag_ids_3' name='post[tag_ids][]' type='checkbox' value='3' />" +
+      "Tag 3</label>" +
+      "<input name='post[tag_ids][]' type='hidden' value='' />"+
+      "<input id='post_id' name='post[id]' type='hidden' value='1' />"
+    end
+
+    assert_dom_equal expected, output_buffer
+  end
+
   def test_form_for_with_file_field_generate_multipart
     Post.send :attr_accessor, :file