JavaScriptGenerator should only sets output_buffer for the duration of the update block

4 files changed, 22 insertions, 12 deletions

diff --git a/actionpack/lib/action_view/helpers/capture_helper.rb b/actionpack/lib/action_view/helpers/capture_helper.rb
index 720e2da8cc..e86ca27f31 100644
--- a/actionpack/lib/action_view/helpers/capture_helper.rb
+++ b/actionpack/lib/action_view/helpers/capture_helper.rb
@@ -122,14 +122,15 @@ module ActionView
         nil
       end
 
-      private
-        def with_output_buffer(buf = '')
-          self.output_buffer, old_buffer = buf, output_buffer
-          yield
-          output_buffer
-        ensure
-          self.output_buffer = old_buffer
-        end
+      # Use an alternate output buffer for the duration of the block.
+      # Defaults to a new empty string.
+      def with_output_buffer(buf = '') #:nodoc:
+        self.output_buffer, old_buffer = buf, output_buffer
+        yield
+        output_buffer
+      ensure
+        self.output_buffer = old_buffer
+      end
     end
   end
 end
diff --git a/actionpack/lib/action_view/helpers/prototype_helper.rb b/actionpack/lib/action_view/helpers/prototype_helper.rb
index edb43844a4..8c8c22dd4a 100644
--- a/actionpack/lib/action_view/helpers/prototype_helper.rb
+++ b/actionpack/lib/action_view/helpers/prototype_helper.rb
@@ -580,9 +580,10 @@ module ActionView
       class JavaScriptGenerator #:nodoc:
         def initialize(context, &block) #:nodoc:
           @context, @lines = context, []
-          @context.output_buffer = @lines if @context
           include_helpers_from_context
-          @context.instance_exec(self, &block)
+          @context.with_output_buffer(@lines) do
+            @context.instance_exec(self, &block)
+          end
         end
 
         private
diff --git a/actionpack/test/template/javascript_helper_test.rb b/actionpack/test/template/javascript_helper_test.rb
index 36dfeba5ed..d41111127b 100644
--- a/actionpack/test/template/javascript_helper_test.rb
+++ b/actionpack/test/template/javascript_helper_test.rb
@@ -3,7 +3,11 @@ require 'abstract_unit'
 class JavaScriptHelperTest < ActionView::TestCase
   tests ActionView::Helpers::JavaScriptHelper
 
-  attr_accessor :output_buffer
+  attr_accessor :template_format, :output_buffer
+
+  def setup
+    @template = self
+  end
 
   def test_escape_javascript
     assert_equal '', escape_javascript(nil)
diff --git a/actionpack/test/template/prototype_helper_test.rb b/actionpack/test/template/prototype_helper_test.rb
index 5528430d80..92cc85703b 100644
--- a/actionpack/test/template/prototype_helper_test.rb
+++ b/actionpack/test/template/prototype_helper_test.rb
@@ -28,7 +28,7 @@ class PrototypeHelperBaseTest < ActionView::TestCase
   attr_accessor :template_format, :output_buffer
 
   def setup
-    @template = nil
+    @template = self
     @controller = Class.new do
       def url_for(options)
         if options.is_a?(String)
@@ -243,8 +243,12 @@ class PrototypeHelperTest < PrototypeHelperBaseTest
   end
 
   def test_update_page
+    old_output_buffer = output_buffer
+
     block = Proc.new { |page| page.replace_html('foo', 'bar') }
     assert_equal create_generator(&block).to_s, update_page(&block)
+
+    assert_equal old_output_buffer, output_buffer
   end
 
   def test_update_page_tag