nail the fact that AttributeError raised in a @Property decorated met…

…hod gets masked by traversal

src/zope/traversing/tests/test_traverser.py

@@ -162,6 +162,16 @@ def testTraversingDoesntFailOnStrings(self):
         self.assertRaises(LocationError, tr.traverse, 'foo/baz')
 
 
+class ExceptionRaiser(C):
+    @property
+    def valueerror(self):
+        raise ValueError('booom')
+
+    @property
+    def attributeerror(self):
+        raise AttributeError('booom')
+
+
 class RestrictedTraverseTests(PlacelessSetup, unittest.TestCase):
     _oldPolicy = None
     _deniedNames = ()
@@ -211,6 +221,24 @@ def testItemDenied(self):
                           folder)
         self.assertEquals(tr.traverse(('folder',)), folder)
 
+    def testException(self):
+        # nail the fact that AttributeError raised in a @property
+        # decorated method gets masked by traversal
+        self.root.foobar = ExceptionRaiser('foobar')
+
+        endInteraction()
+        newInteraction(ParticipationStub('no one'))
+        tr = Traverser(self.root)
+
+        # AttributeError becomes LocationError if there's no __getitem__
+        # on the object
+        self.assertRaises(LocationError, tr.traverse,
+            ('foobar', 'attributeerror'))
+        # Other exceptions raised as usual
+        self.assertRaises(ValueError, tr.traverse,
+            ('foobar', 'valueerror'))
+
+
 class DefaultTraversableTests(unittest.TestCase):
     def testImplementsITraversable(self):
         self.failUnless(ITraversable.providedBy(DefaultTraversable(None)))