ReleaseEngineering:TestingTechniques

vimdiff

Did you know vim has a diff mode? Try running vimdiff file1 file2

Most of the suggestions below combine nicely with vimdiff, or some other diff utility. Get a dump of the output prior to your changes, and then a dump of the output after your changes and run them through vimdiff or your favourite diff utility.

test-masters.sh

buildbot-configs includes a script called test-masters.sh. It will iterate through the list of buildbot master configurations and run buildbot checkconfig on each.

NOTE: You want your PYTHONPATH to point to the path that contains your buildbotcustom checkout and lib/python inside of the tools repo. For example:

export PYTHONPATH=$PYTHONPATH:~/repos:~/repos/tools/lib/python

where ~/repos is where buildbotcustom and tools are checked out.

Run the tests like this:

./test_masters.sh -8

or like this if you want to test the 0.7.x based masters (remember to switch the branch):

./test_masters.sh

Please run this before asking for review, or landing changes!

config.py is executable!

You can run config.py in the mozilla/ or mozilla-tests/ directories and have it spit out the complete configuration for all branches. e.g.

ln -sf production_config localconfig.py
python config.py > orig.txt
hg qpush # Apply my awesome changes
python config.py > new.txt
vimdiff orig.txt new.txt

setup one master and output the steps for it

cd ~/repos/buildbot-confgs
# run ./setup-master.py --list to see the list of masters
rm -rf master_dir; mkdir master_dir; python setup-master.py master_dir pm01-builder
cd master_dir
python ~/repos/releng/braindump/buildbot-related/dump_master.py master.cfg > old
# apply your changes
python ~/repos/releng/braindump/buildbot-related/dump_master.py master.cfg > new
# compare old and new

and here is the changes I do to brainddump:

diff --git a/buildbot-related/dump_master.py b/buildbot-related/dump_master.py
--- a/buildbot-related/dump_master.py
+++ b/buildbot-related/dump_master.py
@@ -31,4 +31,5 @@ print "Builders:"
 for b in g['c']['builders']:
     print b['name'], b['factory'].__class__.__name__
+'''
     for s in b['factory'].steps:
         step_class, args = s
@@ -65,2 +66,3 @@ for s in g['c']['status']:
             d[a] = getattr(s, a)
     print format_objs(s, d)
+'''

builder_list.py / dump_master.py

Our braindump repo has a few useful scripts to help with testing: builder_list.py and dump_master.py.

builder_list.py will take a buildbot master.cfg file as input and output the list of all builders with steps to stdout.

dump_master.py will take a buildbot master.cfg file as input and output the list of all builders with steps, all change sources, all schedulers, and all status plugins to stdout.

To be really thorough, you can run dump_masters.sh, which is like test-masters.sh, except instead of doing just a buildbot checkconfig, it runs dump_master.py on each master configuration. This can take a while to run (over a minute), but is a great way to make sure your changes don't have unintended side-effects.

This is an example on how to use it:

cd ~/repos/buildbot-configs
~/repos/releng/braindump/buildbot-related/dump_masters.sh > old
# apply your patches
~/repos/releng/braindump/buildbot-related/dump_masters.sh > new
diff -pU 8 old new
# or
vimdiff old new

Be not afraid!

... of hacking things to make testing easier. Here's an example of a simple script to output the command for certain status objects. I used this to make sure that my patch was only changing the command for a subset of the status objects.

import re

# Load the buildbot master config
execfile("master.cfg")

for s in c['status']:
    # We only care about status plugins with a 'command' attribute here
    if hasattr(s, 'command'):
        # Strip out 'instance at 0x12345678', it changes between runs
        s = "%s %s %s" % (s, s.command, s.builders)
        s = re.sub("instance at 0x[0-9a-f]+", "", s)
        print s