add respond! action to return arbitrary status/contents as response

Also fix response to return message/contents as string in array, not bare string.

README.md

@@ -40,6 +40,10 @@ Refraction can be installed in a Rails application as a plugin.
 
     $ script/plugin install git://github.com/pivotal/refraction.git
 
+It can also be used as a gem:
+
+    $ gem install refraction
+
 In `environments/production.rb`, add Refraction at or near the top of your middleware stack.
 
     config.middleware.insert_before(::Rack::Lock, ::Refraction, {})
@@ -102,6 +106,17 @@ The `found!` method tells Refraction to return a response with a `302 Found` sta
 URL for the Location header. Like `#rewrite!` it can take either a string or hash argument to set
 the URL or some of its components.
 
+### `RequestContext#respond!(status, headers, content)`
+
+Use `respond!` to return an arbitrary response to the request. This is useful for responding with
+the contents of a static file. For example:
+
+    req.respond!(503, {'Content-Type' => 'text/html'}, File.read(MAINTENANCE_PATH))
+
+The args are largely the same as the contents of a standard Rack response array with the exceptions
+that you don't need to wrap the content in an array, and the Content-Length header is generated so it
+should not be supplied.
+
 ### URL components
 
 The request object provides the following components of the URL for matching requests: `scheme`,

lib/refraction.rb

@@ -26,12 +26,9 @@ def initialize(env)
     end
 
     def response
-      headers = {
-        'Location' => location,
-        'Content-Type' => 'text/plain',
-        'Content-Length' => message.length.to_s
-      }
-      [status, headers, message]
+      headers = @headers || { 'Location' => location, 'Content-Type' => 'text/plain' }
+      headers['Content-Length'] = message.length.to_s
+      [status, headers, [message]]
     end
 
     # URI part accessors
@@ -95,6 +92,13 @@ def found!(options)
       @message = "moved to #{@uri}"
     end
 
+    def respond!(status, headers, content)
+      @action = :respond
+      @status = status
+      @headers = headers
+      @message = content
+    end
+
     def location
       @uri.to_s
     end
@@ -124,7 +128,7 @@ def call(env)
       self.rules.call(context)
 
       case context.action
-      when :permanent, :found
+      when :permanent, :found, :respond
         context.response
       when :rewrite
         env["rack.url_scheme"]                 = context.scheme

spec/refraction_spec.rb

@@ -173,6 +173,24 @@
     end
   end
 
+  describe "generate arbitrary response" do
+    before(:each) do
+      Refraction.configure do |req|
+        req.respond!(503, {'Content-Type' => 'text/plain'}, "Site down for maintenance.")
+      end
+    end
+
+    it "should respond with status, headers and content" do
+      env = Rack::MockRequest.env_for('http://example.com', :method => 'get')
+      app = mock('app')
+      response = Refraction.new(app).call(env)
+      response[0].should == 503
+      response[1]['Content-Length'].to_i.should == "Site down for maintenance.".length
+      response[1]['Content-Type'].should == "text/plain"
+      response[2].should == ["Site down for maintenance."]
+    end
+  end
+
   describe "environment" do
     before(:each) do
       Refraction.configure do |req|