Merge pull request #828 from tahoe-lafs/3440.render-helper

Make the render test helper generally useful

Fixes: ticket:3440

src/allmydata/test/common_web.py

@@ -1,9 +1,26 @@
 
 import treq
-from twisted.internet import defer
+from twisted.internet.defer import (
+    maybeDeferred,
+    inlineCallbacks,
+    returnValue,
+)
 from twisted.web.error import Error
 
-@defer.inlineCallbacks
+from nevow.context import WebContext
+from nevow.testutil import FakeRequest
+from nevow.appserver import (
+    processingFailed,
+    DefaultExceptionHandler,
+)
+from nevow.inevow import (
+    ICanHandleException,
+    IRequest,
+    IResource as INevowResource,
+    IData,
+)
+
+@inlineCallbacks
 def do_http(method, url, **kwargs):
     response = yield treq.request(method, url, persistent=False, **kwargs)
     body = yield treq.content(response)
@@ -11,4 +28,35 @@ def do_http(method, url, **kwargs):
     # https://github.com/twisted/treq/pull/159 has landed
     if 400 <= response.code < 600:
         raise Error(response.code, response=body)
-    defer.returnValue(body)
+    returnValue(body)
+
+
+def render(resource, query_args):
+    """
+    Render (in the manner of the Nevow appserver) a Nevow ``Page`` or a
+    Twisted ``Resource`` against a request with the given query arguments .
+
+    :param resource: The page or resource to render.
+
+    :param query_args: The query arguments to put into the request being
+        rendered.  A mapping from ``bytes`` to ``list`` of ``bytes``.
+
+    :return Deferred: A Deferred that fires with the rendered response body as
+        ``bytes``.
+    """
+    ctx = WebContext(tag=resource)
+    req = FakeRequest(args=query_args)
+    ctx.remember(DefaultExceptionHandler(), ICanHandleException)
+    ctx.remember(req, IRequest)
+    ctx.remember(None, IData)
+
+    def maybe_concat(res):
+        if isinstance(res, bytes):
+            return req.v + res
+        return req.v
+
+    resource = INevowResource(resource)
+    d = maybeDeferred(resource.renderHTTP, ctx)
+    d.addErrback(processingFailed, req, ctx)
+    d.addCallback(maybe_concat)
+    return d

src/allmydata/test/web/test_web.py

@@ -8,24 +8,13 @@ from bs4 import BeautifulSoup
 
 from twisted.application import service
 from twisted.internet import defer
-from twisted.internet.defer import inlineCallbacks, returnValue, maybeDeferred
+from twisted.internet.defer import inlineCallbacks, returnValue
 from twisted.internet.task import Clock
 from twisted.web import client, error, http
 from twisted.python import failure, log
 
-from nevow.context import WebContext
-from nevow.inevow import (
-    ICanHandleException,
-    IRequest,
-    IData,
-)
 from nevow.util import escapeToXML
 from nevow.loaders import stan
-from nevow.testutil import FakeRequest
-from nevow.appserver import (
-    processingFailed,
-    DefaultExceptionHandler,
-)
 
 from allmydata import interfaces, uri, webish
 from allmydata.storage_client import StorageFarmBroker, StubServer
@@ -70,6 +59,7 @@ from ..common_py3 import TimezoneMixin
 from ..common_web import (
     do_http,
     Error,
+    render,
 )
 from ...web.common import (
     humanize_exception,
@@ -670,6 +660,9 @@ class MultiFormatPageTests(TrialTestCase):
     """
     Tests for ``MultiFormatPage``.
     """
+    def render(self, resource, **queryargs):
+        return self.successResultOf(render(resource, queryargs))
+
     def resource(self):
         """
         Create and return an instance of a ``MultiFormatPage`` subclass with two
@@ -686,31 +679,6 @@ class MultiFormatPageTests(TrialTestCase):
         return Content()
 
 
-    def render(self, resource, **query_args):
-        """
-        Render a Nevow ``Page`` against a request with the given query arguments.
-
-        :param resource: The Nevow resource to render.
-
-        :param query_args: The query arguments to put into the request being
-            rendered.  A mapping from ``bytes`` to ``list`` of ``bytes``.
-
-        :return: The rendered response body as ``bytes``.
-        """
-        ctx = WebContext(tag=resource)
-        req = FakeRequest(args=query_args)
-        ctx.remember(DefaultExceptionHandler(), ICanHandleException)
-        ctx.remember(req, IRequest)
-        ctx.remember(None, IData)
-
-        d = maybeDeferred(resource.renderHTTP, ctx)
-        d.addErrback(processingFailed, req, ctx)
-        res = self.successResultOf(d)
-        if isinstance(res, bytes):
-            return req.v + res
-        return req.v
-
-
     def test_select_format(self):
         """
         The ``formatArgument`` attribute of a ``MultiFormatPage`` subclass