turn RecordedWarning into a namedtuple

fixes pytest-dev#2013

_pytest/recwarn.py

@@ -1,12 +1,12 @@
 """ recording warnings during test function execution. """
-
 import inspect
 
 import _pytest._code
 import py
 import sys
 import warnings
 import pytest
+from collections import namedtuple
 
 
 @pytest.yield_fixture
@@ -110,15 +110,10 @@ def warns(expected_warning, *args, **kwargs):
             return func(*args[1:], **kwargs)
 
 
-class RecordedWarning(object):
-    def __init__(self, message, category, filename, lineno, file, line):
-        self.message = message
-        self.category = category
-        self.filename = filename
-        self.lineno = lineno
-        self.file = file
-        self.line = line
-
+RecordedWarning = namedtuple('RecordedWarning', (
+    'message', 'category', 'filename', 'lineno', 'file', 'line',
+))
+
 
 class WarningsRecorder(object):
     """A context manager to record raised warnings.

testing/test_recwarn.py

@@ -203,6 +203,9 @@ def test_record(self):
         assert len(record) == 1
         assert str(record[0].message) == "user"
 
+        print(repr(record[0]))
+        assert str(record[0].message) in repr(record[0])
+
     def test_record_only(self):
         with pytest.warns(None) as record:
             warnings.warn("user", UserWarning)