Got tests to pass with some more changes.

  * request.formats is much simpler now
    * For XHRs or Accept headers with a single item, we use the Accept header
    * For other requests, we use params[:format] or fallback to HTML
    * This is primarily to work around the fact that browsers provide completely
      broken Accept headers, so we have to whitelist the few cases we can
      specifically isolate and treat other requests as coming from the browser
    * For APIs, we can support single-item Accept headers, which disambiguates
      from the browsers
  * Requests to an action that only has an XML template from the browser will
    no longer find the template. This worked previously because most browsers
    provide a catch-all */*, but this was mostly accidental behavior. If you
    want to serve XML, either use the :xml format in links, or explicitly
    specify the XML template: render "template.xml".

6 files changed, 44 insertions, 36 deletions

diff --git a/actionpack/lib/action_controller/metal/rendering_controller.rb b/actionpack/lib/action_controller/metal/rendering_controller.rb
index 46a69b6b57..4da32ca1b3 100644
--- a/actionpack/lib/action_controller/metal/rendering_controller.rb
+++ b/actionpack/lib/action_controller/metal/rendering_controller.rb
@@ -8,12 +8,17 @@ module ActionController
 
     attr_accessor :hash
     def initialize(klass, formats, locale)
+      @formats, @locale = formats, locale
       @hash = [formats, locale].hash
     end
 
     alias_method :eql?, :equal?
+
+    def inspect
+      "#<HashKey -- formats: #{@formats} locale: #{@locale}>"
+    end
   end
-  
+
   module RenderingController
     extend ActiveSupport::Concern
 
@@ -25,7 +30,7 @@ module ActionController
         template_cache.clear
         super
       end
-      
+
       def template_cache
         @template_cache ||= Hash.new {|h,k| h[k] = {} }
       end
@@ -33,16 +38,19 @@ module ActionController
 
     def process_action(*)
       self.formats = request.formats.map {|x| x.to_sym}
-      Thread.current[:format_locale_key] = HashKey.get(self.class, formats, I18n.locale)
+
+      super
+    end
+
+    def _determine_template(*)
       super
     end
 
     def render(options)
+      Thread.current[:format_locale_key] = HashKey.get(self.class, formats, I18n.locale)
+
       super
-      self.content_type ||= begin
-        mime = options[:_template].mime_type
-        formats.include?(mime && mime.to_sym) || formats.include?(:all) ? mime : Mime::Type.lookup_by_extension(formats.first)
-      end.to_s
+      self.content_type ||= options[:_template].mime_type.to_s
       response_body
     end
 
diff --git a/actionpack/lib/action_controller/testing/process.rb b/actionpack/lib/action_controller/testing/process.rb
index 09b1a59254..6bc7d60d76 100644
--- a/actionpack/lib/action_controller/testing/process.rb
+++ b/actionpack/lib/action_controller/testing/process.rb
@@ -148,7 +148,7 @@ module ActionController #:nodoc:
 
     def xml_http_request(request_method, action, parameters = nil, session = nil, flash = nil)
       @request.env['HTTP_X_REQUESTED_WITH'] = 'XMLHttpRequest'
-      @request.env['HTTP_ACCEPT'] =  [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
+      @request.env['HTTP_ACCEPT'] ||=  [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
       returning __send__(request_method, action, parameters, session, flash) do
         @request.env.delete 'HTTP_X_REQUESTED_WITH'
         @request.env.delete 'HTTP_ACCEPT'
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index b23306af62..bff030f0e4 100755
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -106,16 +106,10 @@ module ActionDispatch
       @env["action_dispatch.request.accepts"] ||= begin
         header = @env['HTTP_ACCEPT'].to_s.strip
 
-        fallback = xhr? ? Mime::JS : Mime::HTML
-
         if header.empty?
-          [content_type, fallback, Mime::ALL].compact
+          [content_type]
         else
-          ret = Mime::Type.parse(header)
-          if ret.last == Mime::ALL
-            ret.insert(-2, fallback)
-          end
-          ret
+          Mime::Type.parse(header)
         end
       end
     end
@@ -163,26 +157,20 @@ module ActionDispatch
     #   GET /posts/5       | request.format => Mime::HTML or MIME::JS, or request.accepts.first depending on the value of <tt>ActionController::Base.use_accept_header</tt>
     #
     def format(view_path = [])
-      @env["action_dispatch.request.format"] ||=
-        if parameters[:format]
-                        Mime[parameters[:format]]
-        elsif ActionController::Base.use_accept_header && !(accepts == ONLY_ALL)
-                        accepts.first
-        elsif xhr? then Mime::JS
-        else            Mime::HTML
-        end
+      formats.first
     end
 
     def formats
-      if ActionController::Base.use_accept_header
-        if param = parameters[:format]
-          Array.wrap(Mime[param])
+      accept = @env['HTTP_ACCEPT']
+
+      @env["action_dispatch.request.formats"] ||=
+        if parameters[:format]
+          [Mime[parameters[:format]]]
+        elsif xhr? || (accept && !accept.include?(?,))
+          accepts
         else
-          accepts.dup
+          [Mime::HTML]
         end
-      else
-        [format]
-      end
     end
 
     # Sets the \format by string extension, which can be used to force custom formats
@@ -198,7 +186,7 @@ module ActionDispatch
     #   end
     def format=(extension)
       parameters[:format] = extension.to_s
-      @env["action_dispatch.request.format"] = Mime::Type.lookup_by_extension(parameters[:format])
+      @env["action_dispatch.request.formats"] = [Mime::Type.lookup_by_extension(parameters[:format])]
     end
 
     # Returns a symbolized version of the <tt>:format</tt> parameter of the request.
diff --git a/actionpack/lib/action_view/base.rb b/actionpack/lib/action_view/base.rb
index edfd1fd71c..ec1b07797b 100644
--- a/actionpack/lib/action_view/base.rb
+++ b/actionpack/lib/action_view/base.rb
@@ -175,6 +175,17 @@ module ActionView #:nodoc:
     attr_accessor :controller
     attr_internal :captures
 
+    def reset_formats(formats)
+      @formats = formats
+
+      if defined?(ActionController)
+        # This is expensive, but we need to reset this when the format is updated,
+        # which currently only happens
+        Thread.current[:format_locale_key] =
+          ActionController::HashKey.get(self.class, formats, I18n.locale)
+      end
+    end
+
     class << self
       delegate :erb_trim_mode=, :to => 'ActionView::TemplateHandlers::ERB'
       delegate :logger, :to => 'ActionController::Base', :allow_nil => true
@@ -240,7 +251,7 @@ module ActionView #:nodoc:
     end
 
     def initialize(view_paths = [], assigns_for_first_render = {}, controller = nil, formats = nil)#:nodoc:
-      @formats = formats || [:html]
+      @formats = formats
       @assigns = assigns_for_first_render.each { |key, value| instance_variable_set("@#{key}", value) }
       @controller = controller
       @helpers = self.class.helpers || Module.new
diff --git a/actionpack/lib/action_view/helpers/prototype_helper.rb b/actionpack/lib/action_view/helpers/prototype_helper.rb
index 624b537ad2..03f1dabb4e 100644
--- a/actionpack/lib/action_view/helpers/prototype_helper.rb
+++ b/actionpack/lib/action_view/helpers/prototype_helper.rb
@@ -991,12 +991,13 @@ module ActionView
 
             def render(*options_for_render)
               old_formats = @context && @context.formats
-              @context.formats = [:html] if @context
+
+              @context.reset_formats([:html]) if @context
               Hash === options_for_render.first ?
                 @context.render(*options_for_render) :
                   options_for_render.first.to_s
             ensure
-              @context.formats = old_formats if @context
+              @context.reset_formats(old_formats) if @context
             end
 
             def javascript_object_for(object)
diff --git a/actionpack/lib/action_view/template/resolver.rb b/actionpack/lib/action_view/template/resolver.rb
index 10f664736f..fe657166d5 100644
--- a/actionpack/lib/action_view/template/resolver.rb
+++ b/actionpack/lib/action_view/template/resolver.rb
@@ -42,7 +42,7 @@ module ActionView
 
     def handler_glob
       @handler_glob ||= begin
-        e = TemplateHandlers.extensions.map{|h| ".#{h},"}.join
+        e = TemplateHandlers.extensions.map{|h| ".#{h}"}.join(",")
         "{#{e}}"
       end
     end