fix mishandling of controllers returning an iter evaluating to False …

…(such as

an empty list, which we return for HEAD requests)
fixes #507
thanks mvtellingen, Petr Kobalicek

--HG--
branch : trunk

pylons/wsgiapp.py

@@ -127,7 +127,7 @@ def __call__(self, environ, start_response):
                     log.debug("Transforming legacy Response object into WSGI "
                               "response")
                 return response(environ, start_response)
-            elif response:
+            elif response is not None:
                 return response
 
             raise Exception("No content returned by controller (Did you remember "

tests/test_units/test_controller.py

@@ -116,6 +116,12 @@ def test_header_check(self):
         assert resp.response.headers['Cache-Control'] == 'private'
         assert resp.header('Content-Type') == 'text/plain'
 
+    def test_head(self):
+        self.baseenviron['pylons.routes_dict']['action'] = 'header_check'
+        resp = self.app._gen_request('HEAD', '/')
+        assert '' == resp.body
+        assert resp.header('Content-Type') == 'text/plain'
+
     def test_redirect(self):
         self.baseenviron['pylons.routes_dict']['action'] = 'use_redirect'
         resp = self.app.get('/', status=301)

tests/test_webapps/filestotest/functional_sample_controller_sample4.py

@@ -13,3 +13,7 @@ def test_post(self):
         response = self.app.post(url_for(controller='/sample', action='test_only_post'),
             params={'id':4})
         assert 'It was a post' in response
+
+    def test_head(self):
+        response = self.app._gen_request('HEAD', url_for(controller='/sample'))
+        assert '' == response.body