remove obsolete discussion of Twisted/trial from testing docs

docs/source/development/testing.txt

@@ -27,16 +27,12 b' tests for that subpackage should be skipped if the dependencies are not found.'
 This is very important so users don't get tests failing simply because they
 don't have dependencies.
 
-The testing system we use is a hybrid of nose_ and Twisted's trial_ test runner.
-We use both because nose detects more things than Twisted and allows for more
-flexible (and lighter-weight) ways of writing tests; in particular we've
+The testing system we use is an extension of the nose_ test runner.
+In particular we've
 developed a nose plugin that allows us to paste verbatim IPython sessions and
-test them as doctests, which is extremely important for us.  But the parts of
-IPython that depend on Twisted must be tested using trial, because only trial
-manages the Twisted reactor correctly.
+test them as doctests, which is extremely important for us.
 
 .. _nose: http://code.google.com/p/python-nose
-.. _trial: http://twistedmatrix.com/trac/wiki/TwistedTrial
 
 
 For the impatient: running the tests
@@ -132,13 +128,6 b' When developing, the :option:`--pdb` and :option:`--pdb-failures` of nose are'
 particularly useful, these drop you into an interactive pdb session at the
 point of the error or failure respectively.
 
-To run Twisted-using tests, use the :command:`trial` command on a per file or
-package basis:
-
-.. code-block:: bash
-
-    trial IPython.kernel
-
 .. note::
 
    The system information summary printed above is accessible from the top
@@ -317,20 +306,6 b' problem at hand, since both work)::'
       yield is_smaller(x, y)
       
 
-Writing tests for Twisted-using code
-------------------------------------
-      
-Tests of Twisted [Twisted]_ using code should be written by subclassing the
-``TestCase`` class that comes with ``twisted.trial.unittest``. Furthermore, all
-:class:`Deferred` instances that are created in the test must be properly
-chained and the final one *must* be the return value of the test method.
-
-.. note::
-  
-  The best place to see how to use the testing tools, are the tests for these
-  tools themselves, which live in :mod:`IPython.testing.tests`.
-  
-    
 Design requirements
 ===================