DOC: add documentation of advanced testing.

Author: Ben Cipollini

doc/source/devel/advanced_testing.rst

@@ -0,0 +1,32 @@
+.. -*- mode: rst -*-
+.. ex: set sts=4 ts=4 sw=4 et tw=79:
+  ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ###
+  #
+  #   See COPYING file distributed along with the NiBabel package for the
+  #   copyright and license terms.
+  #
+  ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ###
+
+.. _advanced_testing:
+
+************
+Advanced Testing
+************
+
+Setup
+-----
+
+Before running advanced tests, please update all submodules of nibabel, by running ``git submodule update --init``
+
+
+Long-running tests
+------------------
+
+Long-running tests are not enabled by default, and can be resource-intensive. To run these tests:
+
+* Set environment variable ``NIPY_EXTRA_TESTS=slow``
+* Run ``nosetests``.
+
+Note that some tests may require a machine with >4GB of RAM.
+
+.. include:: ../links_names.txt

doc/source/devel/index.rst

@@ -14,3 +14,4 @@ Developer documentation page
     add_image_format
     devdiscuss
     make_release
+    advanced_testing

doc/source/installation.rst

@@ -114,7 +114,11 @@ Just install the modules by invoking::
 If sudo is not configured (or even installed) you might have to use
 ``su`` instead.
 
-Now fire up Python and try importing the module to see if everything is fine.
+
+Validating your install
+-----------------------
+
+For a basic test of your installation, fire up Python and try importing the module to see if everything is fine.
 It should look something like this::
 
     Python 2.7.8 (v2.7.8:ee879c0ffa11, Jun 29 2014, 21:07:35)
@@ -123,4 +127,9 @@ It should look something like this::
     >>> import nibabel
     >>>
 
+
+To run the nibabel test suite, from the terminal run ``nosetests nibabel`` or ``python -c "import nibabel; nibabel.test()``.
+
+To run an extended test suite that validates ``nibabel`` for long-running and resource-intensive cases, please see :ref:`advanced_testing`.
+
 .. include:: links_names.txt