ActiveResource testing

Hi, I'm trying to make some good testing on active resources, but I've
some trouble with the *post* method.
Basically this is my mock, where I set the POST verb and the expected
URI.

  ActiveResource::HttpMock.respond_to do |mock|
    mock.post "/locations/buildings.xml?description=new-
description&name=new-name", {}, @variable, 201
  end

Now, if I call the post method with the following code (the one I use
into the controller), it says correctly that doesn't found the correct
matching. This happen because in the mock my params are in the query
string, but if I use the save method, the params will be serialized
into an XML flow.

So this is the code.

  Building.new({"name"=>"new-name", "description"=>"new-
description"}).save

and this the error I got is this.

  ActiveResource::InvalidRequestError: No response recorded for
<POST: /locations/buildings.xml [Content-Typeapplication/xml]
  (<?xml version="1.0" encoding="UTF-8"?>
  <building><building><static><name>new-home</name><description>new-
description</description></static></building></building>)>

As I know is not possible to set the body in the mock, so I tried to
use the custom methods, but nothing to do, because as I need to add
the costum method (a mandatory symbol or string that will be added to
the URI) I can't recreate my URI.

For example.

  Building.post(:name, {"name"=>"new-home", "description"=>"new-
description"})

Will give me back this.

  /locations/buildings/name.xml?description=new-description&name=new-
name # ladd the name string!

Also if I set nil it change the URI, and so this break my tests.
Thanks a lot for your time.