Cache tuples (immutable), not lists; others were using this function and were baffled when they mutated the value.

2 files changed, 13 insertions, 7 deletions

diff --git a/repoze/bfg/tests/test_traversal.py b/repoze/bfg/tests/test_traversal.py
index 04dfd1bca..6459ed1af 100644
--- a/repoze/bfg/tests/test_traversal.py
+++ b/repoze/bfg/tests/test_traversal.py
@@ -8,33 +8,39 @@ class SplitPathTests(unittest.TestCase):
         return split_path(path)
         
     def test_path_startswith_endswith(self):
-        self.assertEqual(self._callFUT('/foo/'), [u'foo'])
+        self.assertEqual(self._callFUT('/foo/'), (u'foo',))
 
     def test_empty_elements(self):
-        self.assertEqual(self._callFUT('foo///'), [u'foo'])
+        self.assertEqual(self._callFUT('foo///'), (u'foo',))
 
     def test_onedot(self):
-        self.assertEqual(self._callFUT('foo/./bar'), [u'foo', u'bar'])
+        self.assertEqual(self._callFUT('foo/./bar'), (u'foo', u'bar'))
 
     def test_twodots(self):
-        self.assertEqual(self._callFUT('foo/../bar'), [u'bar'])
+        self.assertEqual(self._callFUT('foo/../bar'), (u'bar',))
 
     def test_element_urllquoted(self):
         self.assertEqual(self._callFUT('/foo/space%20thing/bar'),
-                         [u'foo', u'space thing', u'bar'])
+                         (u'foo', u'space thing', u'bar'))
 
     def test_segments_are_unicode(self):
         result = self._callFUT('/foo/bar')
         self.assertEqual(type(result[0]), unicode)
         self.assertEqual(type(result[1]), unicode)
 
+    def test_same_value_returned_if_cached(self):
+        result1 = self._callFUT('/foo/bar')
+        result2 = self._callFUT('/foo/bar')
+        self.assertEqual(result1, (u'foo', u'bar'))
+        self.assertEqual(result2, (u'foo', u'bar'))
+
     def test_utf8(self):
         import urllib
         la = 'La Pe\xc3\xb1a'
         encoded = urllib.quote(la)
         decoded = unicode(la, 'utf-8')
         path = '/'.join([encoded, encoded])
-        self.assertEqual(self._callFUT(path), [decoded, decoded])
+        self.assertEqual(self._callFUT(path), (decoded, decoded))
         
     def test_utf16(self):
         import urllib
diff --git a/repoze/bfg/traversal.py b/repoze/bfg/traversal.py
index 2d56f9302..7adef4011 100644
--- a/repoze/bfg/traversal.py
+++ b/repoze/bfg/traversal.py
@@ -120,7 +120,7 @@ def split_path(path):
                 raise TypeError('Could not decode path segment %r using the '
                                 'UTF-8 decoding scheme' % segment)
             clean.append(segment)
-    return clean
+    return tuple(clean)
 
 _marker = object()