Merge pull request #4170 from mabelvj/4133-handle-start_url

Raise error when start_url found instead of start_urls.

scrapy/spiders/__init__.py

@@ -57,6 +57,11 @@ class Spider(object_ref):
 
     def start_requests(self):
         cls = self.__class__
+        if not self.start_urls and hasattr(self, 'start_url'):
+            raise AttributeError(
+                "Crawling could not start: 'start_urls' not found "
+                "or empty (but found 'start_url' attribute instead, "
+                "did you miss an 's'?)")
         if method_is_overridden(cls, Spider, 'make_requests_from_url'):
             warnings.warn(
                 "Spider.make_requests_from_url method is deprecated; it "

tests/test_spider.py

@@ -384,6 +384,14 @@ class CrawlSpiderTest(SpiderTest):
         self.assertTrue(hasattr(spider, '_follow_links'))
         self.assertFalse(spider._follow_links)
 
+    def test_start_url(self):
+        spider = self.spider_class("example.com")
+        spider.start_url = 'https://www.example.com'
+
+        with self.assertRaisesRegex(AttributeError,
+                                    r'^Crawling could not start.*$'):
+            list(spider.start_requests())
+
 
 class SitemapSpiderTest(SpiderTest):