During development of a new git commit, locally running a whole unit
or functional test suite to check every minor code change is
prohibitively expensive. For maximum developer productivity and
happiness, it's generally desirable to make the feedback loop of the
traditional red/green cycle as quick as possible.
So add run-tests-for-diff.sh and run-tests.py to the tools/
subdirectory, using a few tricks as explained below to help with this.
run-tests.py takes a list of files on STDIN, filters the list for
tests which can be run in the current tox virtualenv, and then runs
them with the correct stestr options.
run-tests-for-diff.sh is a simple wrapper around run-tests.py which
determines which tests to run using output from "git diff". This
allows running only the test files changed/added in the working tree:
tools/run-tests-for-diff.sh
or by a single commit:
tools/run-tests-for-diff.sh mybranch^!
or a range of commits, e.g. a branch containing a whole patch series
for a blueprint:
tools/run-tests-for-diff.sh gerrit/master..bp/my-blueprint
It supports the same "-HEAD" invocation syntax as flake8wrap.sh (as
used by the "fast8" tox environment):
tools/run-tests-for-diff.sh -HEAD
run-tests.py uses two tricks to make test runs as quick as possible:
1. It's (already) possible to speed up running of tests by
source'ing the "activate" file for the desired tox virtualenv,
e.g.
source .tox/py36/bin/activate
and then running stestr directly. This saves a few seconds by
skipping the overhead introduced by running tox.
2. When only one test file needs to be run, specifying the -n option
to stestr will skip the costly test discovery phase, saving
several more valuable seconds.
Future commits could build on top of this work, harnessing a framework
such as watchdog / watchmedo[0] or Guard[1] in order to automatically
run relevant tests every time your editor saves changes to a .py file.
[0] https://github.com/gorakhargosh/watchdog - Python-based
[1] https://guardgem.org - probably best in class, but Ruby-based so
maybe unacceptable for use within Nova.
Change-Id: I9a9bda5d29bbb8d8d77f769cd1abf7c42a18c36b
5df748b2ed