- When two views were registered with differering ``for`` interfaces

  or classes, and the ``for`` of first view registered was a
  superclass of the second, the ``repoze.bfg` view machinery would
  incorrectly associate the two views with the same "multiview".
  Multiviews are meant to be collections of views that have *exactly*
  the same for/request/viewname values, without taking inheritance
  into account.  Symptom: wrong view callable found even when you had
  correctly specified a ``for_`` interface/class during view
  configuration for one or both view configurations.

2 files changed, 83 insertions, 2 deletions

diff --git a/repoze/bfg/configuration.py b/repoze/bfg/configuration.py
index d474c557f..e6d421c34 100644
--- a/repoze/bfg/configuration.py
+++ b/repoze/bfg/configuration.py
@@ -586,15 +586,44 @@ class Configurator(object):
             r_for_ = implementedBy(r_for_)
         if not IInterface.providedBy(r_request_type):
             r_request_type = implementedBy(r_request_type)
-        old_view = self.registry.adapters.lookup((r_for_, r_request_type),
-                                                 IView, name=name)
+
+        registered = self.registry.adapters.registered
+
+        # A multiviews is a set of views which are registered for
+        # exactly the same context type/request type/name triad.  Each
+        # consituent view in a multiview differs only by the
+        # predicates which it possesses.
+
+        # To find a previously registered view for a context
+        # type/request type/name triad, we need to use the
+        # ``registered`` method of the adapter registry rather than
+        # ``lookup``.  ``registered`` ignores interface inheritance
+        # for the required and provided arguments, returning only a
+        # view registered previously with the *exact* triad we pass
+        # in.
+
+        # We need to do this three times, because we use three
+        # different interfaces as the ``provided`` interface while
+        # doing registrations, and ``registered`` performs exact
+        # matches on all the arguments it receives.
+        
+        old_view = registered((r_for_, r_request_type), IView, name)
+        if old_view is None:
+            old_view = registered((r_for_, r_request_type), ISecuredView, name)
+            if old_view is None:
+                old_view = registered((r_for_, r_request_type), IMultiView,
+                                      name)
         if old_view is None:
+            # No component was registered for any of our I*View
+            # interfaces exactly; this is the first view for this
+            # triad.  We don't need a multiview.
             if hasattr(derived_view, '__call_permissive__'):
                 view_iface = ISecuredView
             else:
                 view_iface = IView
             self.registry.registerAdapter(derived_view, (for_, request_type),
                                           view_iface, name, info=_info)
+            final_view = derived_view
         else:
             # XXX we could try to be more efficient here and register
             # a non-secured view for a multiview if none of the
@@ -614,6 +643,16 @@ class Configurator(object):
                                                   name=name)
             self.registry.registerAdapter(multiview, (for_, request_type),
                                           IMultiView, name, info=_info)
+            final_view = multiview
+
+        if name == 'edit.html':
+            import pprint
+            pprint.pprint ({'for':r_for_,
+                            'request_type':r_request_type,
+                            'old_view':old_view,
+                            'final_view':final_view,
+                            'numpreds':len(predicates)})
+            print
 
     def add_route(self, name, path, view=None, view_for=None,
                   permission=None, factory=None, for_=None,
diff --git a/repoze/bfg/tests/test_configuration.py b/repoze/bfg/tests/test_configuration.py
index 43d2cb153..da2f1d2c4 100644
--- a/repoze/bfg/tests/test_configuration.py
+++ b/repoze/bfg/tests/test_configuration.py
@@ -547,6 +547,48 @@ class ConfiguratorTests(unittest.TestCase):
         self.assertEqual(wrapper.views, [(view2, None)])
         self.assertEqual(wrapper(None, None), 'OK1')
 
+    def test_add_view_multiview_context_superclass_then_subclass(self):
+        from zope.interface import Interface
+        from repoze.bfg.interfaces import IRequest
+        from repoze.bfg.interfaces import IView
+        from repoze.bfg.interfaces import IMultiView
+        class ISuper(Interface):
+            pass
+        class ISub(ISuper):
+            pass
+        view = lambda *arg: 'OK'
+        view2 = lambda *arg: 'OK2'
+        config = self._makeOne()
+        config.registry.registerAdapter(
+            view, (ISuper, IRequest), IView, name='')
+        config.add_view(view=view2, for_=ISub)
+        wrapper = self._getViewCallable(config, ISuper, IRequest)
+        self.failIf(IMultiView.providedBy(wrapper))
+        self.assertEqual(wrapper(None, None), 'OK')
+        wrapper = self._getViewCallable(config, ISub, IRequest)
+        self.failIf(IMultiView.providedBy(wrapper))
+        self.assertEqual(wrapper(None, None), 'OK2')
+
+    def test_add_view_multiview_request_superclass_then_subclass(self):
+        from zope.interface import Interface
+        from repoze.bfg.interfaces import IRequest
+        from repoze.bfg.interfaces import IView
+        from repoze.bfg.interfaces import IMultiView
+        class ISubRequest(IRequest):
+            pass
+        view = lambda *arg: 'OK'
+        view2 = lambda *arg: 'OK2'
+        config = self._makeOne()
+        config.registry.registerAdapter(
+            view, (Interface, IRequest), IView, name='')
+        config.add_view(view=view2, request_type=ISubRequest)
+        wrapper = self._getViewCallable(config, Interface, IRequest)
+        self.failIf(IMultiView.providedBy(wrapper))
+        self.assertEqual(wrapper(None, None), 'OK')
+        wrapper = self._getViewCallable(config, Interface, ISubRequest)
+        self.failIf(IMultiView.providedBy(wrapper))
+        self.assertEqual(wrapper(None, None), 'OK2')
+
     def test_add_view_multiview_call_ordering(self):
         from zope.interface import directlyProvides
         def view1(context, request): return 'view1'