For an HTTP 405 on generic methods, attempt to specify an Allow header.

Change-Id: I726d698fc014c21cc1e43a09a129384fa1f1235f

pecan/core.py

@@ -631,6 +631,12 @@ class PecanBase(object):
             else:
                 if not isinstance(e, exc.HTTPException):
                     raise
+
+            # if this is an HTTP 405, attempt to specify an Allow header
+            if isinstance(e, exc.HTTPMethodNotAllowed) and controller:
+                allowed_methods = _cfg(controller).get('allowed_methods', [])
+                if allowed_methods:
+                    state.response.allow = sorted(allowed_methods)
         finally:
             # handle "after" hooks
             self.handle_hooks(

pecan/decorators.py

@@ -16,6 +16,7 @@ def when_for(controller):
             expose(**kw)(f)
             _cfg(f)['generic_handler'] = True
             controller._pecan['generic_handlers'][method.upper()] = f
+            controller._pecan['allowed_methods'].append(method.upper())
             return f
         return decorate
     return when
@@ -56,6 +57,7 @@ def expose(template=None,
         if generic:
             cfg['generic'] = True
             cfg['generic_handlers'] = dict(DEFAULT=f)
+            cfg['allowed_methods'] = []
             f.when = when_for(f)
 
         # store the arguments for this controller method

pecan/tests/test_generic.py

@@ -6,7 +6,7 @@ except:
 
 from six import b as b_
 
-from pecan import Pecan, expose
+from pecan import Pecan, expose, abort
 from pecan.tests import PecanTestCase
 
 
@@ -37,3 +37,26 @@ class TestGeneric(PecanTestCase):
 
         r = app.get('/do_get', status=404)
         assert r.status_int == 404
+
+    def test_generic_allow_header(self):
+        class RootController(object):
+            @expose(generic=True)
+            def index(self):
+                abort(405)
+
+            @index.when(method='POST', template='json')
+            def do_post(self):
+                return dict(result='POST')
+
+            @index.when(method='GET')
+            def do_get(self):
+                return 'GET'
+
+            @index.when(method='PATCH')
+            def do_patch(self):
+                return 'PATCH'
+
+        app = TestApp(Pecan(RootController()))
+        r = app.delete('/', expect_errors=True)
+        assert r.status_int == 405
+        assert r.headers['Allow'] == 'GET, PATCH, POST'