Refactor how we get error text and add tests

rejected/consumer.py

@@ -859,7 +859,7 @@ def execute(self, message_in, measurement):
             self.logger.error('ConsumerException processing delivery %s: %s',
                               message_in.delivery_tag, error)
             self._measurement.set_tag('exception', error.__class__.__name__)
-            error_text = ' '.join(error.args).strip()
+            error_text = self._get_error_text(error)
             if error_text:
                 self._measurement.set_tag('error', error_text)
             raise gen.Return(data.CONSUMER_EXCEPTION)
@@ -868,7 +868,7 @@ def execute(self, message_in, measurement):
             self.logger.debug('MessageException processing delivery %s: %s',
                               message_in.delivery_tag, error)
             self._measurement.set_tag('exception', error.__class__.__name__)
-            error_text = ' '.join(error.args).strip()
+            error_text = self._get_error_text(error)
             if error_text:
                 self._measurement.set_tag('error', error_text)
             raise gen.Return(data.MESSAGE_EXCEPTION)
@@ -877,7 +877,7 @@ def execute(self, message_in, measurement):
             self.logger.debug('ProcessingException processing delivery %s: %s',
                               message_in.delivery_tag, error)
             self._measurement.set_tag('exception', error.__class__.__name__)
-            error_text = ' '.join(error.args).strip()
+            error_text = self._get_error_text(error)
             if error_text:
                 self._measurement.set_tag('error', error_text)
             self._republish_processing_error(error_text)
@@ -981,6 +981,20 @@ def _clear(self):
         self._message = None
         self._message_body = None
 
+    @staticmethod
+    def _get_error_text(error):
+        """Return the arguments passed into an exception as a space delimited
+        string (or None).
+
+        :param Exception error: The exception to process
+        :rtype: str
+
+        """
+        try:
+            return ' '.join([str(a) for a in error.args]).strip() or None
+        except (TypeError, AttributeError):
+            return
+
     @staticmethod
     def _get_pika_properties(properties_in):
         """Return a :class:`pika.spec.BasicProperties` object for a

tests/test_consumer.py

@@ -1,15 +1,16 @@
 # coding=utf-8
 """Tests for rejected.consumer"""
-from tornado import gen
+import collections
 import json
+
+from tornado import gen, testing
 import mock
 try:
     import unittest2 as unittest
 except ImportError:
     import unittest
 
 from . import mocks
-from tornado import testing
 
 from rejected import consumer, data
 
@@ -167,6 +168,23 @@ def test_user_id_property(self):
         self.assertEqual(self.obj.user_id, mocks.PROPERTIES.user_id)
 
 
+class TestErrorText(unittest.TestCase):
+
+    def test_string_value(self):
+        error = consumer.ProcessingException('error text')
+        self.assertEqual(consumer.Consumer._get_error_text(error),
+                         'error text')
+
+    def test_multiple_values(self):
+        error = consumer.ProcessingException('error text', 10)
+        self.assertEqual(consumer.Consumer._get_error_text(error),
+                         'error text 10')
+
+    def test_empty_values(self):
+        error = consumer.ProcessingException()
+        self.assertIsNone(consumer.Consumer._get_error_text(error))
+
+
 class TestSmartConsumer(consumer.SmartConsumer):
     def process(self):
         pass