report warnings

tests/test_crawler.py

@@ -182,8 +182,12 @@ class CrawlerRunnerTestCase(BaseCrawlerTest):
                 'SPIDER_MANAGER_CLASS': 'tests.test_crawler.CustomSpiderLoader'
             })
             self.assertIsInstance(runner.spider_loader, CustomSpiderLoader)
-            self.assertEqual(len(w), 1)
+            is_one_warning = len(w) == 1
+            if not is_one_warning:
+                for warning in w:
+                    print(warning)
             self.assertIn('Please use SPIDER_LOADER_CLASS', str(w[0].message))
+            self.assertTrue(is_one_warning)
 
     def test_crawl_rejects_spider_objects(self):
         with raises(ValueError):