Allow users to customize the behavior of flask.abort

Prior to werkzeug 0.12.2, it was possible to manipulate the status code
to exception type maps flask used by invoking::

    flask.abort.mapping.update(mapping)

This brings that back by creating a flask specific
werkzeug.exceptions.Aborter object and exposing it as flask.aborter. It
also implements a flask.abort function so that the correct docstring is
exposed::

    flask.aborter.mapping.update(mapping)

flask/__init__.py

@@ -14,7 +14,6 @@ __version__ = '0.13-dev'
 
 # utilities we import from Werkzeug and Jinja2 that are unused
 # in the module but are exported as public interface.
-from werkzeug.exceptions import abort
 from werkzeug.utils import redirect
 from jinja2 import Markup, escape
 
@@ -22,7 +21,7 @@ from .app import Flask, Request, Response
 from .config import Config
 from .helpers import url_for, flash, send_file, send_from_directory, \
      get_flashed_messages, get_template_attribute, make_response, safe_join, \
-     stream_with_context
+     stream_with_context, aborter, abort
 from .globals import current_app, g, request, session, _request_ctx_stack, \
      _app_ctx_stack
 from .ctx import has_request_context, has_app_context, \

flask/helpers.py

@@ -20,6 +20,7 @@ from zlib import adler32
 from threading import RLock
 import unicodedata
 from werkzeug.routing import BuildError
+from werkzeug.exceptions import Aborter
 from functools import update_wrapper
 
 try:
@@ -1017,3 +1018,27 @@ def is_ip(value):
             return True
 
     return False
+
+
+def abort(status, *args, **kwargs):
+    '''
+    Raises an :py:exc:`werkzeug.exceptions.HTTPException` for the given
+    status::
+
+        abort(404)  # 404 Not Found
+        abort(Response('Hello World'))
+
+    If a status code is given it's looked up in the list of exceptions and will
+    raise that exception::
+
+       abort(404)
+       abort(Response('Hello World'))
+
+    To modify the status code to exception mapping, you can use
+    aborter.mapping.update::
+
+       aborter.mapping.update({404: MyCustom404Exception})
+    '''
+    return aborter(status, *args, **kwargs)
+
+aborter = Aborter()

tests/test_helpers.py

@@ -15,7 +15,7 @@ import uuid
 
 import pytest
 from werkzeug.datastructures import Range
-from werkzeug.exceptions import BadRequest, NotFound
+from werkzeug.exceptions import BadRequest, NotFound, HTTPException
 from werkzeug.http import http_date, parse_cache_control_header, \
     parse_options_header
 
@@ -886,3 +886,28 @@ class TestHelpers(object):
             assert rv.status_code == 200
             assert rv.data == b'Hello'
             assert rv.mimetype == 'text/html'
+
+
+class TestCustomAborterMapping(object):
+    def test_custom_aborter_mapping(self, app, client):
+        app.config['DEBUG'] = True
+        app.config['TRAP_BAD_REQUEST_ERRORS'] = False
+
+        class CustomNotFound(HTTPException):
+            code = 404
+            description = 'CUSTOM ABORTER MAPPINGS'
+
+        @app.route('/', methods=['GET'])
+        def index():
+            flask.abort(404)
+
+        try:
+            original = flask.aborter.mapping.get(404, '__UNSET__')
+            flask.aborter.mapping.update({404: CustomNotFound})
+
+            rv = client.get('/')
+            assert rv.status_code == 404
+            assert 'CUSTOM ABORTER MAPPINGS' in rv.data
+        finally:
+            if original != '__UNSET__':
+                flask.aborter.mapping.update({404: original})