Add support to use pdb with tox

Change-Id: Id1b208843ab038a38f389097baafe985d5ea92e9

README.rst

@@ -296,7 +296,25 @@ Read the HTML documentation
 
   Open doc/html/index.html in a browser
 
-4.3 Upgrade
+4.3 Debugging unit tests
+------------------------
+
+In order to break into the debugger from a unit test we need to insert
+a breaking point to the code:
+
+.. code-block:: python
+
+  import pdb; pdb.set_trace()
+
+Then run ``tox`` with the debug environment as one of the following::
+
+  tox -e debug
+  tox -e debug test_file_name.TestClass.test_name
+
+For more information see the `oslotest documentation
+<http://docs.openstack.org/developer/oslotest/features.html#debugging-with-oslo-debug-helper>`_.
+
+4.4 Upgrade
 -----------
 
 Here are the instructions for upgrading to a new release of the

test-requirements.txt

@@ -7,6 +7,7 @@ coverage>=3.6 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=2.0 # BSD
 mox3>=0.7.0 # Apache-2.0
+oslotest>=1.10.0 # Apache-2.0
 requests-mock>=1.0 # Apache-2.0
 python-subunit>=0.0.18 # Apache-2.0/BSD
 testrepository>=0.0.18 # Apache-2.0/BSD

tox.ini

@@ -31,6 +31,9 @@ commands = {posargs}
 [testenv:cover]
 commands = python setup.py testr --coverage --testr-args='{posargs}'
 
+[testenv:debug]
+commands = oslo_debug_helper -t congress/tests {posargs}
+
 [testenv:bench]
 setenv =
    TEST_BENCHMARK=true
@@ -56,4 +59,4 @@ setenv = PYTHONHASHSEED=0
 commands = python setup.py build_sphinx
 
 [testenv:releasenotes]
-commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
+commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html