request (Rack::MockSession)

    # File lib/rack/mock_session.rb, line 20
        def request(uri, env)
          env["HTTP_COOKIE"] ||= cookie_jar.for(uri)
          @last_request = Rack::Request.new(env)
          status, headers, body = @app.call(@last_request.env)
          @last_response = MockResponse.new(status, headers, body, env["rack.errors"].flush)
          cookie_jar.merge(last_response.headers["Set-Cookie"], uri)

          @last_response
        end