Update docs about testing.

Add an entry to the HACKING file about testr. While in there, noticed a
reference to the now-defunct nova/testing dir. Fixed that, moved the testing
README into nova/tests and remove the nova/testing dir.

Change-Id: Ibf6fb82658ba73eee9123fa53b340d0b72afb292

HACKING.rst

@@ -218,7 +218,27 @@ submitted bug fix does have a unit test, be sure to add a new one that fails
 without the patch and passes with the patch.
 
 For more information on creating unit tests and utilizing the testing
-infrastructure in OpenStack Nova, please read nova/testing/README.rst.
+infrastructure in OpenStack Nova, please read nova/tests/README.rst.
+
+
+Running Tests
+-------------
+The testing system is based on a combination of tox and testr. The canonical
+approach to running tests is to simply run the command `tox`. This will
+create virtual environments, populate them with depenedencies and run all of
+the tests that OpenStack CI systems run. Behind the scenes, tox is running
+`testr run --parallel`, but is set up such that you can supply any additional
+testr arguments that are needed to tox. For example, you can run:
+`tox -- --analyze-isolation` to cause tox to tell testr to add
+--analyze-isolation to its argument list.
+
+It is also possible to run the tests inside of a virtual environment
+you have created, or it is possible that you have all of the dependencies
+installed locally already. In this case, you can interact with the testr
+command directly. Running `testr run` will run the entire test suite. `testr
+run --parallel` will run it in parallel (this is the default incantation tox
+uses.) More information about testr can be found at:
+http://wiki.openstack.org/testr
 
 
 openstack-common

nova/tests/README.rst

@@ -2,16 +2,8 @@
 OpenStack Nova Testing Infrastructure
 =====================================
 
-A note of clarification is in order, to help those who are new to testing in
-OpenStack nova:
-
-- actual unit tests are created in the "tests" directory;
-- the "testing" directory is used to house the infrastructure needed to support
-  testing in OpenStack Nova.
-
 This README file attempts to provide current and prospective contributors with
-everything they need to know in order to start creating unit tests and
-utilizing the convenience code provided in nova.testing.
+everything they need to know in order to start creating unit tests for nova.
 
 Note: the content for the rest of this file will be added as the work items in
 the following blueprint are completed: