Raise generic errors (catch all InternalError) when using WSGI

CHANGES.rst

@@ -36,6 +36,9 @@ Bugfixes
 - Accept bytes and text as cookie value.
   (`#263 <https://github.com/zopefoundation/Zope/pull/263>`_)
 
+- always raise InternalError when using WSGI
+  (`#280 <https://github.com/zopefoundation/Zope/pull/280>`)
+
 
 4.0b4 (2018-04-23)
 ------------------

src/Testing/tests/test_testbrowser.py

@@ -98,9 +98,10 @@ def test_handle_errors_true(self):
         self.folder._setObject('stub', ExceptionStub())
         browser = Browser()
 
-        with self.assertRaises(HTTPError):
+        # HTTP errors only for WSGI
+        with self.assertRaises(ValueError):
             browser.open('http://localhost/test_folder_1_/stub')
-        self.assertTrue(browser.headers['status'].startswith('500'))
+        self.assertIsNone(browser.contents)
 
         with self.assertRaises(HTTPError):
             browser.open('http://localhost/nothing-is-here')
@@ -165,8 +166,10 @@ def test_raise_http_errors_false(self):
         browser = Browser()
         browser.raiseHttpErrors = False
 
-        browser.open('http://localhost/test_folder_1_/stub')
-        self.assertTrue(browser.headers['status'].startswith('500'))
+        # HTTP errors only for WSGI
+        with self.assertRaises(ValueError):
+            browser.open('http://localhost/test_folder_1_/stub')
+        self.assertIsNone(browser.contents)
 
         browser.open('http://localhost/nothing-is-here')
         self.assertTrue(browser.headers['status'].startswith('404'))

src/ZPublisher/httpexceptions.py

@@ -34,10 +34,18 @@ def __call__(self, environ, start_response):
         except HTTPException as exc:
             return exc(environ, start_response)
         except Exception as exc:
-            if self.debug_mode or environ.get('x-wsgiorg.throw_errors', False):
+            if self.debug_mode:
                 # In debug mode, let the web server log a real
                 # traceback
                 raise
+            elif environ.get('wsgi.errors') is not None:
+                # s. https://www.python.org/dev/peps/pep-0333/#id27
+                # Imho the catch all InternalError is the generic error case
+                # that should not be handled by the application but
+                # rather the WSGI server. This way the error along with
+                # the traceback ends up in the configured logs.
+                # 'wsgi.errors' must be defined according to PEP-0333
+                raise
             return self.catch_all_response(exc)(environ, start_response)
 
     def catch_all_response(self, exc):