Magicks to make Flask MethodViews more testable

resource.py

class Resource(MethodView):
    """
    Represents an abstract RESTful resource. Concrete resources should
    extend from this class and expose methods for each supported HTTP
    method. If a resource is invoked with an unsupported HTTP method,
    the API will return a response with status 405 Method Not Allowed.
    Otherwise the appropriate method is called and passed all arguments
    from the url rule used when adding the resource to an Api instance. See
    :meth:`~flask.ext.restful.Api.add_resource` for details.
    """
    representations = None
    method_decorators = []

    def dispatch_request(self, *args, **kwargs):

        # Taken from flask
        #noinspection PyUnresolvedReferences
        meth = getattr(self, request.method.lower(), None)
        if meth is None and request.method == 'HEAD':
            meth = getattr(self, 'get', None)
        assert meth is not None, 'Unimplemented method %r' % request.method

        meth = inject_globals(meth)

        for decorator in self.method_decorators:
            meth = decorator(meth)

        resp = meth(*args, **kwargs)

        if isinstance(resp, ResponseBase):  # There may be a better way to test
            return resp

        representations = self.representations or {}

        #noinspection PyUnresolvedReferences
        for mediatype in self.mediatypes():
            if mediatype in representations:
                data, code, headers = unpack(resp)
                resp = representations[mediatype](data, code, headers)
                resp.headers['Content-Type'] = mediatype
                return resp

        return resp


def inject_globals(func):
    """Pass the Flask global proxy objects into a view function.
    
    View functions should then rely on using the Flask globals passed by the
    injector decorator. This will make Flask view functions more testable
    since the tests can just create simple `werkzeug.wrappers.Response` 
    instances and pass them instead of having to go through the full WSGI
    environment/routing used by `app.test_client`.
    """
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        flask_globals = {
            'g': g,
            'app': current_app,
            'request': request,
            'session': session,
        }
        kwargs.update(flask_globals)
        return func(*args, **kwargs)
    return wrapper

user.py

#!/usr/bin/env python

from flask import abort

from resource import Resource

from models import User

class UserResource(Resource):
    def get(self, user_id=0, **kwargs):
        user = User.get_by_username(user_id)

        if not user:
            abort(404)

        return user.to_json()

    def post(self, user_id=0, **kwargs):
        request = kwargs['request']
        user = User.get_by_username(user_id)

        if not user:
            abort(404)

        user.update(**request.args)
        return user.to_json()

    def delete(self, user_id=0, **kwargs):
        user = User.get_by_username(user_id)

        if not user:
            abort(404)

        user.delete()
        return {'message': 'deleted', 'status': 204}, 204