Merge pull request #75 from seequent/#74-fix-adaption-of-interface-only

Fix adaption error

pure_interface.py

@@ -668,6 +668,8 @@ def interface_only(cls, implementation):
     def adapt(cls, obj, allow_implicit=False, interface_only=None):
         if interface_only is None:
             interface_only = is_development
+        if isinstance(obj, _ImplementationWrapper):
+            obj = obj._ImplementationWrapper__impl
         if InterfaceType.provided_by(cls, obj, allow_implicit=allow_implicit):
             adapter = no_adaption
         else:

tests/test_adaption.py

@@ -10,6 +10,11 @@
     import mock
 
 
+class ITalker(pure_interface.Interface):
+    def talk(self):
+        pass
+
+
 class ISpeaker(pure_interface.Interface):
     def speak(self, volume):
         pass
@@ -24,7 +29,7 @@ def speak(self, volume):
         return 'speak'
 
 
-class Talker(object):
+class Talker(ITalker, object):
     def talk(self):
         return 'talk'
 
@@ -326,3 +331,12 @@ def test_optional_adapt(self):
             adapt.assert_called_once_with(ISpeaker, a_speaker, allow_implicit=allow, interface_only=interface_only)
             self.assertIs(s, adapt.return_value)
             self.assertIsNone(none, 'optional_adapt(None) did not return None')
+
+    def test_adapt_interface_only(self):
+        talker = Talker()
+        talker_only = ITalker.adapt(talker)
+        self.assertIsInstance(talker_only, pure_interface._ImplementationWrapper)
+        try:
+            ISpeaker.adapt(talker_only)
+        except:
+            self.fail('adaption of interface only failed.')