diff --git a/actionpack/lib/action_view/helpers/deprecated_block_helpers.rb b/actionpack/lib/action_view/helpers/deprecated_block_helpers.rb
index ffbffbf25e..3d0657e873 100644
--- a/actionpack/lib/action_view/helpers/deprecated_block_helpers.rb
+++ b/actionpack/lib/action_view/helpers/deprecated_block_helpers.rb
@@ -6,6 +6,7 @@ module ActionView
       include ActionView::Helpers::TagHelper
       include ActionView::Helpers::TextHelper
       include ActionView::Helpers::JavaScriptHelper
+      include ActionView::Helpers::FormHelper
 
       def content_tag(*, &block)
         block_called_from_erb?(block) ? safe_concat(super) : super
@@ -15,6 +16,22 @@ module ActionView
         block_called_from_erb?(block) ? safe_concat(super) : super
       end
 
+      def form_for(*, &block)
+        block_called_from_erb?(block) ? safe_concat(super) : super
+      end
+
+      def form_tag(*, &block)
+        block_called_from_erb?(block) ? safe_concat(super) : super
+      end
+
+      def fields_for(*, &block)
+        block_called_from_erb?(block) ? safe_concat(super) : super
+      end
+
+      def field_set_tag(*, &block)
+        block_called_from_erb?(block) ? safe_concat(super) : super
+      end
+
       BLOCK_CALLED_FROM_ERB = 'defined? __in_erb_template'
 
       if RUBY_VERSION < '1.9.0'
diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 742e873a49..48df26efaa 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -92,6 +92,10 @@ module ActionView
     # link:classes/ActionView/Helpers/DateHelper.html, and
     # link:classes/ActionView/Helpers/ActiveRecordHelper.html
     module FormHelper
+      extend ActiveSupport::Concern
+
+      include FormTagHelper
+
       # Creates a form and a scope around a specific model object that is used
       # as a base for questioning about values for the fields.
       #
@@ -309,9 +313,9 @@ module ActionView
 
         options[:html][:remote] = true if options.delete(:remote)
 
-        safe_concat(form_tag(options.delete(:url) || {}, options.delete(:html) || {}))
-        fields_for(object_name, *(args << options), &proc)
-        safe_concat('</form>')
+        output = form_tag(options.delete(:url) || {}, options.delete(:html) || {})
+        output << fields_for(object_name, *(args << options), &proc)
+        output.safe_concat('</form>')
       end
 
       def apply_form_for_options!(object_or_array, options) #:nodoc:
@@ -528,7 +532,10 @@ module ActionView
         end
 
         builder = options[:builder] || ActionView::Base.default_form_builder
-        yield builder.new(object_name, object, self, options, block)
+
+        with_output_buffer do
+          yield builder.new(object_name, object, self, options, block)
+        end
       end
 
       # Returns a label tag tailored for labelling an input field for a specified attribute (identified by +method+) on an object
@@ -1183,9 +1190,11 @@ module ActionView
 
           if association.is_a?(Array)
             explicit_child_index = options[:child_index]
-            association.map do |child|
-              fields_for_nested_model("#{name}[#{explicit_child_index || nested_child_index(name)}]", child, options, block)
-            end.join
+            output = ActiveSupport::SafeBuffer.new
+            association.each do |child|
+              output << fields_for_nested_model("#{name}[#{explicit_child_index || nested_child_index(name)}]", child, options, block)
+            end
+            output
           elsif association
             fields_for_nested_model(name, association, options, block)
           end
diff --git a/actionpack/lib/action_view/helpers/form_options_helper.rb b/actionpack/lib/action_view/helpers/form_options_helper.rb
index 7f74be27cb..7039ecd233 100644
--- a/actionpack/lib/action_view/helpers/form_options_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_options_helper.rb
@@ -97,7 +97,9 @@ module ActionView
     #   </select>
     #
     module FormOptionsHelper
+      # ERB::Util can mask some helpers like textilize. Make sure to include them.
       include ERB::Util
+      include TextHelper
 
       # Create a select tag and a series of contained option tags for the provided object and method.
       # The option currently held by the object will be selected, provided that the object is available.
diff --git a/actionpack/lib/action_view/helpers/form_tag_helper.rb b/actionpack/lib/action_view/helpers/form_tag_helper.rb
index 7dcaee7e34..573733ffea 100644
--- a/actionpack/lib/action_view/helpers/form_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_tag_helper.rb
@@ -10,6 +10,11 @@ module ActionView
     # NOTE: The HTML options <tt>disabled</tt>, <tt>readonly</tt>, and <tt>multiple</tt> can all be treated as booleans. So specifying
     # <tt>:disabled => true</tt> will give <tt>disabled="disabled"</tt>.
     module FormTagHelper
+      extend ActiveSupport::Concern
+
+      include UrlHelper
+      include TextHelper
+
       # Starts a form tag that points the action to an url configured with <tt>url_for_options</tt> just like
       # ActionController::Base#url_for. The method for the form defaults to POST.
       #
@@ -441,10 +446,10 @@ module ActionView
       #   # => <fieldset class="format"><p><input id="name" name="name" type="text" /></p></fieldset>
       def field_set_tag(legend = nil, options = nil, &block)
         content = capture(&block)
-        safe_concat(tag(:fieldset, options, true))
-        safe_concat(content_tag(:legend, legend)) unless legend.blank?
-        concat(content)
-        safe_concat("</fieldset>")
+        output = tag(:fieldset, options, true)
+        output.safe_concat(content_tag(:legend, legend)) unless legend.blank?
+        output.concat(content)
+        output.safe_concat("</fieldset>")
       end
 
       private
@@ -477,9 +482,10 @@ module ActionView
 
         def form_tag_in_block(html_options, &block)
           content = capture(&block)
-          safe_concat(form_tag_html(html_options))
-          concat(content)
-          safe_concat("</form>")
+          output = ActiveSupport::SafeBuffer.new
+          output.safe_concat(form_tag_html(html_options))
+          output << content
+          output.safe_concat("</form>")
         end
 
         def token_tag
diff --git a/actionpack/lib/action_view/template/handlers/erb.rb b/actionpack/lib/action_view/template/handlers/erb.rb
index 3fcae167ff..937694ce8e 100644
--- a/actionpack/lib/action_view/template/handlers/erb.rb
+++ b/actionpack/lib/action_view/template/handlers/erb.rb
@@ -28,10 +28,18 @@ module ActionView
       @buffer.to_s
     end
 
+    def to_str
+      @buffer.to_str
+    end
+
     def empty?
       @buffer.empty?
     end
 
+    def html_safe?
+      @buffer.html_safe?
+    end
+
     if "".respond_to?(:force_encoding)
       def force_encoding(encoding)
         @buffer.force_encoding(encoding)
diff --git a/actionpack/test/template/date_helper_test.rb b/actionpack/test/template/date_helper_test.rb
index 9a2d490854..da2477b6f8 100644
--- a/actionpack/test/template/date_helper_test.rb
+++ b/actionpack/test/template/date_helper_test.rb
@@ -1250,7 +1250,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.date_select(:written_on)
     end
 
@@ -1266,7 +1266,7 @@ class DateHelperTest < ActionView::TestCase
     @post.written_on = Date.new(2004, 6, 15)
     id = 27
 
-    fields_for :post, @post, :index => id do |f|
+    output_buffer = fields_for :post, @post, :index => id do |f|
       concat f.date_select(:written_on)
     end
 
@@ -1282,7 +1282,7 @@ class DateHelperTest < ActionView::TestCase
     @post.written_on = Date.new(2004, 6, 15)
     id = nil
 
-    fields_for :post, @post, :index => id do |f|
+    output_buffer = fields_for :post, @post, :index => id do |f|
       concat f.date_select(:written_on)
     end
 
@@ -1478,7 +1478,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Date.new(2004, 6, 15)
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.date_select(:written_on, {}, :class => 'selector')
     end
 
@@ -1642,7 +1642,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.written_on = Time.local(2004, 6, 15, 15, 16, 35)
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.time_select(:written_on, {}, :class => 'selector')
     end
 
@@ -1816,7 +1816,7 @@ class DateHelperTest < ActionView::TestCase
     @post = Post.new
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.datetime_select(:updated_at, {}, :class => 'selector')
     end
 
@@ -2052,7 +2052,7 @@ class DateHelperTest < ActionView::TestCase
     @post.updated_at = Time.local(2004, 6, 15, 16, 35)
     id = 456
 
-    fields_for :post, @post, :index => id do |f|
+    output_buffer = fields_for :post, @post, :index => id do |f|
       concat f.datetime_select(:updated_at)
     end
 
diff --git a/actionpack/test/template/erb/tag_helper_test.rb b/actionpack/test/template/erb/tag_helper_test.rb
index d9ca828b43..b91539ef0b 100644
--- a/actionpack/test/template/erb/tag_helper_test.rb
+++ b/actionpack/test/template/erb/tag_helper_test.rb
@@ -1,6 +1,28 @@
 require "abstract_unit"
 
 module ERBTest
+  class ViewContext
+    mock_controller = Class.new do
+      include SharedTestRoutes.url_helpers
+    end
+
+    include ActionView::Helpers::TagHelper
+    include ActionView::Helpers::JavaScriptHelper
+    include ActionView::Helpers::FormHelper
+
+    attr_accessor :output_buffer
+
+    def protect_against_forgery?() false end
+
+    define_method(:controller) do
+      mock_controller.new
+    end
+  end
+
+  class DeprecatedViewContext < ViewContext
+    include ActionView::Helpers::DeprecatedBlockHelpers
+  end
+
   module SharedTagHelpers
     extend ActiveSupport::Testing::Declarative
 
@@ -22,16 +44,21 @@ module ERBTest
       expected_output = "<script id=\"the_js_tag\" type=\"text/javascript\">\n//<![CDATA[\nalert('Hello')\n//]]>\n</script>"
       assert_equal expected_output, render_content("javascript_tag(:id => 'the_js_tag')", "alert('Hello')")
     end
+
+    test "percent equals works with form tags" do
+      expected_output = "<form action=\"foo\" method=\"post\">hello</form>"
+      assert_equal expected_output, render_content("form_tag('foo')", "<%= 'hello' %>")
+    end
+
+    test "percent equals works with fieldset tags" do
+      expected_output = "<fieldset><legend>foo</legend>hello</fieldset>"
+      assert_equal expected_output, render_content("field_set_tag('foo')", "<%= 'hello' %>")
+    end
   end
 
   class TagHelperTest < ActiveSupport::TestCase
     def context
-      Class.new do
-        include ActionView::Helpers::TagHelper
-        include ActionView::Helpers::JavaScriptHelper
-
-        attr_accessor :output_buffer
-      end
+      ViewContext
     end
 
     def block_helper(str, rest)
@@ -43,12 +70,7 @@ module ERBTest
 
   class DeprecatedTagHelperTest < ActiveSupport::TestCase
     def context
-      Class.new do
-        include ActionView::Helpers::TagHelper
-        include ActionView::Helpers::JavaScriptHelper
-        include ActionView::Helpers::DeprecatedBlockHelpers
-        attr_accessor :output_buffer
-      end
+      DeprecatedViewContext
     end
 
     def block_helper(str, rest)
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index d143c39c9c..7c5ccfd6ed 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -4,6 +4,10 @@ require 'controller/fake_models'
 class FormHelperTest < ActionView::TestCase
   tests ActionView::Helpers::FormHelper
 
+  def form_for(*)
+    @output_buffer = super
+  end
+
   def setup
     super
 
@@ -590,9 +594,9 @@ class FormHelperTest < ActionView::TestCase
 
   def test_nested_fields_for
     form_for(:post, @post) do |f|
-      f.fields_for(:comment, @post) do |c|
+      concat f.fields_for(:comment, @post) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -605,9 +609,9 @@ class FormHelperTest < ActionView::TestCase
   def test_nested_fields_for_with_nested_collections
     form_for('post[]', @post) do |f|
       concat f.text_field(:title)
-      f.fields_for('comment[]', @comment) do |c|
+      concat f.fields_for('comment[]', @comment) { |c|
         concat c.text_field(:name)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -621,9 +625,9 @@ class FormHelperTest < ActionView::TestCase
   def test_nested_fields_for_with_index_and_parent_fields
     form_for('post', @post, :index => 1) do |c|
       concat c.text_field(:title)
-      c.fields_for('comment', @comment, :index => 1) do |r|
+      concat c.fields_for('comment', @comment, :index => 1) { |r|
         concat r.text_field(:name)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -635,10 +639,10 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_form_for_with_index_and_nested_fields_for
-    form_for(:post, @post, :index => 1) do |f|
-      f.fields_for(:comment, @post) do |c|
+    output_buffer = form_for(:post, @post, :index => 1) do |f|
+      concat f.fields_for(:comment, @post) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -650,9 +654,9 @@ class FormHelperTest < ActionView::TestCase
 
   def test_nested_fields_for_with_index_on_both
     form_for(:post, @post, :index => 1) do |f|
-      f.fields_for(:comment, @post, :index => 5) do |c|
+      concat f.fields_for(:comment, @post, :index => 5) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -664,9 +668,9 @@ class FormHelperTest < ActionView::TestCase
 
   def test_nested_fields_for_with_auto_index
     form_for("post[]", @post) do |f|
-      f.fields_for(:comment, @post) do |c|
+      concat f.fields_for(:comment, @post) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -678,9 +682,9 @@ class FormHelperTest < ActionView::TestCase
 
   def test_nested_fields_for_with_index_radio_button
     form_for(:post, @post) do |f|
-      f.fields_for(:comment, @post, :index => 5) do |c|
+      concat f.fields_for(:comment, @post, :index => 5) { |c|
         concat c.radio_button(:title, "hello")
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -692,9 +696,9 @@ class FormHelperTest < ActionView::TestCase
 
   def test_nested_fields_for_with_auto_index_on_both
     form_for("post[]", @post) do |f|
-      f.fields_for("comment[]", @post) do |c|
+      concat f.fields_for("comment[]", @post) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -705,16 +709,16 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_nested_fields_for_with_index_and_auto_index
-    form_for("post[]", @post) do |f|
-      f.fields_for(:comment, @post, :index => 5) do |c|
+    output_buffer = form_for("post[]", @post) do |f|
+      concat f.fields_for(:comment, @post, :index => 5) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
-    form_for(:post, @post, :index => 1) do |f|
-      f.fields_for("comment[]", @post) do |c|
+    output_buffer << form_for(:post, @post, :index => 1) do |f|
+      concat f.fields_for("comment[]", @post) { |c|
         concat c.text_field(:title)
-      end
+      }
     end
 
     expected = "<form action='http://www.example.com' method='post'>" +
@@ -732,9 +736,9 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:author) do |af|
+      concat f.fields_for(:author) { |af|
         concat af.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -759,9 +763,9 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:author) do |af|
+      concat f.fields_for(:author) { |af|
         concat af.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -778,10 +782,10 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:author) do |af|
+      concat f.fields_for(:author) { |af|
         concat af.hidden_field(:id)
         concat af.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -799,9 +803,9 @@ class FormHelperTest < ActionView::TestCase
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
       @post.comments.each do |comment|
-        f.fields_for(:comments, comment) do |cf|
+        concat f.fields_for(:comments, comment) { |cf|
           concat cf.text_field(:name)
-        end
+        }
       end
     end
 
@@ -822,10 +826,10 @@ class FormHelperTest < ActionView::TestCase
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
       @post.comments.each do |comment|
-        f.fields_for(:comments, comment) do |cf|
+        concat f.fields_for(:comments, comment) { |cf|
           concat cf.hidden_field(:id)
           concat cf.text_field(:name)
-        end
+        }
       end
     end
 
@@ -846,9 +850,9 @@ class FormHelperTest < ActionView::TestCase
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
       @post.comments.each do |comment|
-        f.fields_for(:comments, comment) do |cf|
+        concat f.fields_for(:comments, comment) { |cf|
           concat cf.text_field(:name)
-        end
+        }
       end
     end
 
@@ -867,9 +871,9 @@ class FormHelperTest < ActionView::TestCase
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
       @post.comments.each do |comment|
-        f.fields_for(:comments, comment) do |cf|
+        concat f.fields_for(:comments, comment) { |cf|
           concat cf.text_field(:name)
-        end
+        }
       end
     end
 
@@ -903,9 +907,9 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:comments, @post.comments) do |cf|
+      concat f.fields_for(:comments, @post.comments) { |cf|
         concat cf.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -925,9 +929,9 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:comments, comments) do |cf|
+      concat f.fields_for(:comments, comments) { |cf|
         concat cf.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -947,10 +951,10 @@ class FormHelperTest < ActionView::TestCase
 
     form_for(:post, @post) do |f|
       concat f.text_field(:title)
-      f.fields_for(:comments) do |cf|
+      concat f.fields_for(:comments) { |cf|
         concat cf.text_field(:name)
         yielded_comments << cf.object
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -968,9 +972,9 @@ class FormHelperTest < ActionView::TestCase
     @post.comments = []
 
     form_for(:post, @post) do |f|
-      f.fields_for(:comments, Comment.new(321), :child_index => 'abc') do |cf|
+      concat f.fields_for(:comments, Comment.new(321), :child_index => 'abc') { |cf|
         concat cf.text_field(:name)
-      end
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -988,24 +992,24 @@ class FormHelperTest < ActionView::TestCase
     @post.tags[0].relevances = []
     @post.tags[1].relevances = []
     form_for(:post, @post) do |f|
-      f.fields_for(:comments, @post.comments[0]) do |cf|
+      concat f.fields_for(:comments, @post.comments[0]) { |cf|
         concat cf.text_field(:name)
-        cf.fields_for(:relevances, CommentRelevance.new(314)) do |crf|
+        concat cf.fields_for(:relevances, CommentRelevance.new(314)) { |crf|
           concat crf.text_field(:value)
-        end
-      end
-      f.fields_for(:tags, @post.tags[0]) do |tf|
+        }
+      }
+      concat f.fields_for(:tags, @post.tags[0]) { |tf|
         concat tf.text_field(:value)
-        tf.fields_for(:relevances, TagRelevance.new(3141)) do |trf|
+        concat tf.fields_for(:relevances, TagRelevance.new(3141)) { |trf|
           concat trf.text_field(:value)
-        end
-      end
-      f.fields_for('tags', @post.tags[1]) do |tf|
+        }
+      }
+      concat f.fields_for('tags', @post.tags[1]) { |tf|
         concat tf.text_field(:value)
-        tf.fields_for(:relevances, TagRelevance.new(31415)) do |trf|
+        concat tf.fields_for(:relevances, TagRelevance.new(31415)) { |trf|
           concat trf.text_field(:value)
-        end
-      end
+        }
+      }
     end
 
     expected = '<form action="http://www.example.com" method="post">' +
@@ -1027,7 +1031,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for
-    fields_for(:post, @post) do |f|
+    output_buffer = fields_for(:post, @post) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1043,7 +1047,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_with_index
-    fields_for("post[]", @post) do |f|
+    output_buffer = fields_for("post[]", @post) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1059,7 +1063,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_with_nil_index_option_override
-    fields_for("post[]", @post, :index => nil) do |f|
+    output_buffer = fields_for("post[]", @post, :index => nil) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1075,7 +1079,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_with_index_option_override
-    fields_for("post[]", @post, :index => "abc") do |f|
+    output_buffer = fields_for("post[]", @post, :index => "abc") do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1091,7 +1095,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_without_object
-    fields_for(:post) do |f|
+    output_buffer = fields_for(:post) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1107,7 +1111,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_with_only_object
-    fields_for(@post) do |f|
+    output_buffer = fields_for(@post) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
@@ -1123,7 +1127,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_object_with_bracketed_name
-    fields_for("author[post]", @post) do |f|
+    output_buffer = fields_for("author[post]", @post) do |f|
       concat f.label(:title)
       concat f.text_field(:title)
     end
@@ -1134,7 +1138,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_object_with_bracketed_name_and_index
-    fields_for("author[post]", @post, :index => 1) do |f|
+    output_buffer = fields_for("author[post]", @post, :index => 1) do |f|
       concat f.label(:title)
       concat f.text_field(:title)
     end
@@ -1153,9 +1157,9 @@ class FormHelperTest < ActionView::TestCase
       concat post_form.text_field(:title)
       concat post_form.text_area(:body)
 
-      fields_for(:parent_post, @post) do |parent_fields|
+      concat fields_for(:parent_post, @post) { |parent_fields|
         concat parent_fields.check_box(:secret)
-      end
+      }
     end
 
     expected =
@@ -1174,9 +1178,9 @@ class FormHelperTest < ActionView::TestCase
       concat post_form.text_field(:title)
       concat post_form.text_area(:body)
 
-      post_form.fields_for(@comment) do |comment_fields|
+      concat post_form.fields_for(@comment) { |comment_fields|
         concat comment_fields.text_field(:name)
-      end
+      }
     end
 
     expected =
@@ -1273,7 +1277,7 @@ class FormHelperTest < ActionView::TestCase
   end
 
   def test_fields_for_with_labelled_builder
-    fields_for(:post, @post, :builder => LabelledFormBuilder) do |f|
+    output_buffer = fields_for(:post, @post, :builder => LabelledFormBuilder) do |f|
       concat f.text_field(:title)
       concat f.text_area(:body)
       concat f.check_box(:secret)
diff --git a/actionpack/test/template/form_options_helper_test.rb b/actionpack/test/template/form_options_helper_test.rb
index aa40e46aa8..5799e3db53 100644
--- a/actionpack/test/template/form_options_helper_test.rb
+++ b/actionpack/test/template/form_options_helper_test.rb
@@ -293,7 +293,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     @post.category = "<mus>"
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.select(:category, %w( abe <mus> hest))
     end
   
@@ -307,7 +307,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     @post.category = "<mus>"
 
-    fields_for :post, @post, :index => 108 do |f|
+    output_buffer = fields_for :post, @post, :index => 108 do |f|
       concat f.select(:category, %w( abe <mus> hest))
     end
 
@@ -322,7 +322,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post.category = "<mus>"
     def @post.to_param; 108; end
 
-    fields_for "post[]", @post do |f|
+    output_buffer = fields_for "post[]", @post do |f|
       concat f.select(:category, %w( abe <mus> hest))
     end
 
@@ -336,7 +336,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     options = "<option value=\"abe\">abe</option><option value=\"mus\">mus</option><option value=\"hest\">hest</option>"
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.select(:category, options, :prompt => 'The prompt')
     end
 
@@ -462,7 +462,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     @post.author_name = "Babe"
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.collection_select(:author_name, dummy_posts, :author_name, :author_name)
     end
   
@@ -476,7 +476,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     @post.author_name = "Babe"
 
-    fields_for :post, @post, :index => 815 do |f|
+    output_buffer = fields_for :post, @post, :index => 815 do |f|
       concat f.collection_select(:author_name, dummy_posts, :author_name, :author_name)
     end
 
@@ -491,7 +491,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post.author_name = "Babe"
     def @post.to_param; 815; end
 
-    fields_for "post[]", @post do |f|
+    output_buffer = fields_for "post[]", @post do |f|
       concat f.collection_select(:author_name, dummy_posts, :author_name, :author_name)
     end
 
@@ -570,7 +570,7 @@ class FormOptionsHelperTest < ActionView::TestCase
   def test_time_zone_select_under_fields_for
     @firm = Firm.new("D")
 
-    fields_for :firm, @firm do |f|
+    output_buffer = fields_for :firm, @firm do |f|
       concat f.time_zone_select(:time_zone)
     end
   
@@ -589,7 +589,7 @@ class FormOptionsHelperTest < ActionView::TestCase
   def test_time_zone_select_under_fields_for_with_index
     @firm = Firm.new("D")
 
-    fields_for :firm, @firm, :index => 305 do |f|
+    output_buffer = fields_for :firm, @firm, :index => 305 do |f|
       concat f.time_zone_select(:time_zone)
     end
 
@@ -609,7 +609,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @firm = Firm.new("D")
     def @firm.to_param; 305; end
 
-    fields_for "firm[]", @firm do |f|
+    output_buffer = fields_for "firm[]", @firm do |f|
       concat f.time_zone_select(:time_zone)
     end
 
@@ -787,7 +787,7 @@ class FormOptionsHelperTest < ActionView::TestCase
     @post = Post.new
     @post.origin = 'dk'
 
-    fields_for :post, @post do |f|
+    output_buffer = fields_for :post, @post do |f|
       concat f.grouped_collection_select("origin", @continents, :countries, :continent_name, :country_id, :country_name)
     end
 
diff --git a/actionpack/test/template/form_tag_helper_test.rb b/actionpack/test/template/form_tag_helper_test.rb
index c7d4bc986c..868a35c476 100644
--- a/actionpack/test/template/form_tag_helper_test.rb
+++ b/actionpack/test/template/form_tag_helper_test.rb
@@ -59,16 +59,14 @@ class FormTagHelperTest < ActionView::TestCase
   end
 
   def test_form_tag_with_block_in_erb
-    __in_erb_template = ''
-    form_tag("http://example.com") { concat "Hello world!" }
+    output_buffer = form_tag("http://example.com") { concat "Hello world!" }
 
     expected = %(<form action="http://example.com" method="post">Hello world!</form>)
     assert_dom_equal expected, output_buffer
   end
 
   def test_form_tag_with_block_and_method_in_erb
-    __in_erb_template = ''
-    form_tag("http://example.com", :method => :put) { concat "Hello world!" }
+    output_buffer = form_tag("http://example.com", :method => :put) { concat "Hello world!" }
 
     expected = %(<form action="http://example.com" method="post"><div style='margin:0;padding:0;display:inline'><input type="hidden" name="_method" value="put" /></div>Hello world!</form>)
     assert_dom_equal expected, output_buffer
@@ -332,26 +330,22 @@ class FormTagHelperTest < ActionView::TestCase
   end
 
   def test_field_set_tag_in_erb
-    __in_erb_template = ''
-    field_set_tag("Your details") { concat "Hello world!" }
+    output_buffer = field_set_tag("Your details") { concat "Hello world!" }
 
     expected = %(<fieldset><legend>Your details</legend>Hello world!</fieldset>)
     assert_dom_equal expected, output_buffer
 
-    self.output_buffer = ''.html_safe
-    field_set_tag { concat "Hello world!" }
+    output_buffer = field_set_tag { concat "Hello world!" }
 
     expected = %(<fieldset>Hello world!</fieldset>)
     assert_dom_equal expected, output_buffer
 
-    self.output_buffer = ''.html_safe
-    field_set_tag('') { concat "Hello world!" }
+    output_buffer = field_set_tag('') { concat "Hello world!" }
 
     expected = %(<fieldset>Hello world!</fieldset>)
     assert_dom_equal expected, output_buffer
 
-    self.output_buffer = ''.html_safe
-    field_set_tag('', :class => 'format') { concat "Hello world!" }
+    output_buffer = field_set_tag('', :class => 'format') { concat "Hello world!" }
 
     expected = %(<fieldset class="format">Hello world!</fieldset>)
     assert_dom_equal expected, output_buffer