restored stats_spider_{opened,closing,closed} signals in backwards compatibility mode

docs/news.rst

@@ -6,7 +6,7 @@ Release notes
 
 Scrapy changes:
 
-- major Stats Collection refactoring: removed separation of global/per-spider stats, removed stats-related signals (``stats_spider_opened``, etc). Stats are much simpler now, backwards compatibility is kept on the Stats Collector API.
+- major Stats Collection refactoring: removed separation of global/per-spider stats, removed stats-related signals (``stats_spider_opened``, etc). Stats are much simpler now, backwards compatibility is kept on the Stats Collector API and signals.
 - added :meth:`~scrapy.contrib.spidermiddleware.SpiderMiddleware.process_start_requests` method to spider middlewares
 - dropped Signals singleton. Signals should now be accesed through the Crawler.signals attribute. See the signals documentation for more info.
 - dropped Signals singleton. Signals should now be accesed through the Crawler.signals attribute. See the signals documentation for more info.

scrapy/core/engine.py

@@ -262,8 +262,10 @@ class ExecutionEngine(object):
         dfd.addBoth(lambda _: slot.scheduler.close(reason))
         dfd.addErrback(log.err, spider=spider)
 
+        # XXX: spider_stats argument was added for backwards compatibility with
+        # stats collection refactoring added in 0.15. it should be removed in 0.17.
         dfd.addBoth(lambda _: self.signals.send_catch_log_deferred(signal=signals.spider_closed, \
-            spider=spider, reason=reason))
+            spider=spider, reason=reason, spider_stats=self.crawler.stats.get_stats()))
         dfd.addErrback(log.err, spider=spider)
 
         dfd.addBoth(lambda _: self.crawler.stats.close_spider(spider, reason=reason))

scrapy/signals.py

@@ -17,4 +17,8 @@ response_downloaded = object()
 item_scraped = object()
 item_dropped = object()
 
+stats_spider_opened = spider_opened
+stats_spider_closing = spider_closed
+stats_spider_closed = spider_closed
+
 item_passed = item_scraped # for backwards compatibility

scrapy/tests/test_engine.py

@@ -197,6 +197,7 @@ class EngineTest(unittest.TestCase):
                          self.run.signals_catched[signals.spider_opened])
         self.assertEqual({'spider': self.run.spider},
                          self.run.signals_catched[signals.spider_idle])
+        self.run.signals_catched[signals.spider_closed].pop('spider_stats', None) # XXX: remove for scrapy 0.17
         self.assertEqual({'spider': self.run.spider, 'reason': 'finished'},
                          self.run.signals_catched[signals.spider_closed])