Add a failing test.

1 files changed, 19 insertions, 0 deletions

diff --git a/pyramid/tests/test_config/test_settings.py b/pyramid/tests/test_config/test_settings.py
index 2dbe9b1bb..d6fb8de67 100644
--- a/pyramid/tests/test_config/test_settings.py
+++ b/pyramid/tests/test_config/test_settings.py
@@ -1,5 +1,6 @@
 import unittest
 
+
 class TestSettingsConfiguratorMixin(unittest.TestCase):
     def _makeOne(self, *arg, **kw):
         from pyramid.config import Configurator
@@ -63,6 +64,24 @@ class TestSettingsConfiguratorMixin(unittest.TestCase):
         settings = reg.getUtility(ISettings)
         self.assertEqual(settings['a'], 1)
 
+    def test_settings_parameter_dict_is_never_updated(self):
+        class ReadOnlyDict(dict):
+            def __readonly__(self, *args, **kwargs):
+                raise RuntimeError("Cannot modify ReadOnlyDict")
+            __setitem__ = __readonly__
+            __delitem__ = __readonly__
+            pop = __readonly__
+            popitem = __readonly__
+            clear = __readonly__
+            update = __readonly__
+            setdefault = __readonly__
+            del __readonly__
+
+        initial = ReadOnlyDict()
+        config = self._makeOne(settings=initial)
+        config._set_settings({'a': '1'})
+
+
 class TestSettings(unittest.TestCase):
 
     def _getTargetClass(self):