Add contributor notes on how to use pdb with tests
@@ -211,3 +211,31 @@ Therefore, it is preferable to use:
.. rubric:: Footnotes
.. [#f1] See :doc:`jenkins`.
+
+
+Debugging
+---------
+
+**Debugging unit tests**
+
+It is possible to attach a debugger to unit tests.
+
+First, modify the test you want to debug by adding the
+following to the test code itself:
+
+.. code-block:: python
+
+ import pdb
+ pdb.set_trace()
+
+Then run the unit test with pdb enabled:
+
+.. code-block:: bash
+
+ source .tox/py35/bin/activate
+ testr init
+ ostestr --pdb cinder.tests.unit.test_volume_utils
+ # or
+ ostestr -n cinder.tests.unit.test_volume_utils
+ # or
+ ostestr -n cinder/tests/unit/test_context.py
