text: from unittest import TestCase
  from urllib.parse import urlparse
  import warnings
  
  from scrapy.http import Response, Request
  from scrapy.spiders import Spider
  from scrapy.spidermiddlewares.offsite import OffsiteMiddleware, URLWarning
  from scrapy.utils.test import get_crawler
  
  
  class TestOffsiteMiddleware(TestCase):
  
      def setUp(self):
          crawler = get_crawler(Spider)
          self.spider = crawler._create_spider(**self._get_spiderargs())
          self.mw = OffsiteMiddleware.from_crawler(crawler)
          self.mw.spider_opened(self.spider)
  
      def _get_spiderargs(self):
          return dict(name='foo', allowed_domains=['scrapytest.org', 'scrapy.org', 'scrapy.test.org'])
  
      def test_process_spider_output(self):
          res = Response('http://scrapytest.org')
  
          onsite_reqs = [Request('http://scrapytest.org/1'),
                         Request('http://scrapy.org/1'),
                         Request('http://sub.scrapy.org/1'),
                         Request('http://offsite.tld/letmepass', dont_filter=True),
                         Request('http://scrapy.test.org/')]
          offsite_reqs = [Request('http://scrapy2.org'),
                         Request('http://offsite.tld/'),
                         Request('http://offsite.tld/scrapytest.org'),
                         Request('http://offsite.tld/rogue.scrapytest.org'),
                         Request('http://rogue.scrapytest.org.haha.com'),
                         Request('http://roguescrapytest.org'),
                         Request('http://test.org/'),
                         Request('http://notscrapy.test.org/')]
          reqs = onsite_reqs + offsite_reqs
  
          out = list(self.mw.process_spider_output(res, reqs, self.spider))
          self.assertEqual(out, onsite_reqs)
  
  
  class TestOffsiteMiddleware2(TestOffsiteMiddleware):
  
      def _get_spiderargs(self):
          return dict(name='foo', allowed_domains=None)
  
      def test_process_spider_output(self):
          res = Response('http://scrapytest.org')
          reqs = [Request('http://a.com/b.html'), Request('http://b.com/1')]
          out = list(self.mw.process_spider_output(res, reqs, self.spider))
          self.assertEqual(out, reqs)
  
  
  class TestOffsiteMiddleware3(TestOffsiteMiddleware2):
  
      def _get_spider(self):
          return Spider('foo')
  
  
  class TestOffsiteMiddleware4(TestOffsiteMiddleware3):
  
      def _get_spider(self):
        bad_hostname = urlparse('http:////scrapytest.org').hostname
        return dict(name='foo', allowed_domains=['scrapytest.org', None, bad_hostname])
  
      def test_process_spider_output(self):
        res = Response('http://scrapytest.org')
        reqs = [Request('http://scrapytest.org/1')]
        out = list(self.mw.process_spider_output(res, reqs, self.spider))
        self.assertEqual(out, reqs)
  
  
  class TestOffsiteMiddleware5(TestOffsiteMiddleware4):
      
      def test_get_host_regex(self):
          self.spider.allowed_domains = ['http://scrapytest.org', 'scrapy.org', 'scrapy.test.org']
          with warnings.catch_warnings(record=True) as w:
              warnings.simplefilter("always")
              self.mw.get_host_regex(self.spider)
              assert issubclass(w[-1].category, URLWarning)
  