diff --git a/actionpack/lib/action_controller/testing/process.rb b/actionpack/lib/action_controller/testing/process.rb
index 16275371ad75f815ef53bdca3e24c1cb2e35518f..c532a67e78543fc9b0d30a8e119d3cf4a93684b3 100644
--- a/actionpack/lib/action_controller/testing/process.rb
+++ b/actionpack/lib/action_controller/testing/process.rb
@@ -14,8 +14,8 @@ def initialize(env = {})
       super(Rack::MockRequest.env_for("/").merge(env))
 
       @query_parameters   = {}
-      @env['rack.session'] = TestSession.new
-      @env['rack.session.options'] = TestSession::DEFAULT_OPTIONS.merge(:id => ActiveSupport::SecureRandom.hex(16))
+      self.session = TestSession.new
+      self.session_options = TestSession::DEFAULT_OPTIONS.merge(:id => ActiveSupport::SecureRandom.hex(16))
 
       initialize_default_values
       initialize_containers