fixed bug when using log.start() with log level module constants instead of string names, and added regression tests

scrapy/log.py

@@ -34,15 +34,24 @@ log_level = DEBUG
 
 started = False
 
+def _get_log_level(level_name_or_id=None):
+    if level_name_or_id is None:
+        lvlname = settings['LOG_LEVEL'] or settings['LOGLEVEL']
+        return globals()[lvlname]
+    elif isinstance(level_name_or_id, int) and 0 <= level_name_or_id <= 5:
+        return level_name_or_id
+    elif isinstance(level_name_or_id, basestring):
+        return globals()[level_name_or_id]
+    else:
+        raise ValueError("Unknown log level: %r" % level_name_or_id)
+
 def start(logfile=None, loglevel=None, logstdout=None):
     """Initialize and start logging facility"""
     global log_level, started
 
-    # set loglevel
-    loglevel = loglevel or settings['LOG_LEVEL'] or settings['LOGLEVEL']
-    log_level = globals()[loglevel] if loglevel else DEBUG
     if started or not settings.getbool('LOG_ENABLED'):
         return
+    log_level = _get_log_level(loglevel)
     started = True
 
     # set log observer

scrapy/tests/test_log.py

@@ -0,0 +1,17 @@
+import unittest
+
+from scrapy import log
+from scrapy.conf import settings
+
+class ItemTest(unittest.TestCase):
+
+    def test_get_log_level(self):
+        default_log_level = getattr(log, settings['LOG_LEVEL'])
+        self.assertEqual(log._get_log_level(), default_log_level)
+        self.assertEqual(log._get_log_level('WARNING'), log.WARNING)
+        self.assertEqual(log._get_log_level(log.WARNING), log.WARNING)
+        self.assertRaises(ValueError, log._get_log_level, 99999)
+        self.assertRaises(ValueError, log._get_log_level, object())
+
+if __name__ == "__main__":
+    unittest.main()