test_downloadermiddleware_uriuserinfo: restore needed instance variable

tests/test_downloadermiddleware_uriuserinfo.py

@@ -2,6 +2,7 @@ import unittest
 
 from scrapy.http import Request
 from scrapy.downloadermiddlewares.uriuserinfo import UriUserinfoMiddleware
+from scrapy.spiders import Spider
 
 
 class BaseTestCase:
@@ -10,6 +11,7 @@ class BaseTestCase:
 
         def setUp(self):
             self.mw = UriUserinfoMiddleware()
+            self.spider = Spider('bar')
 
         def tearDown(self):
             del self.mw