initialize ivars, refactor recycle! to call initialize

actionpack/lib/action_controller/test_case.rb

@@ -220,15 +220,7 @@ def default_env
 
   class TestResponse < ActionDispatch::TestResponse
     def recycle!
-      @status = 200
-      @header = {}
-      @writer = lambda { |x| @body << x }
-      @block = nil
-      @length = 0
-      @body = []
-      @committed = false
-      @charset = @content_type = nil
-      @request = @template = nil
+      initialize
     end
   end
 

actionpack/lib/action_dispatch/http/response.rb

@@ -74,6 +74,8 @@ def initialize(status = 200, header = {}, body = [])
       @blank        = false
       @cv           = new_cond
       @committed    = false
+      @content_type = nil
+      @charset      = nil
 
       if content_type = self[CONTENT_TYPE]
         type, charset = content_type.split(/;\s*charset=/)