Note that the instructions below assume that you have the Chromium depot tools installed and configured. If you don't, you do not pass go, and you cannot collect your $200.
Best is to use git to hack on anything, you can set up a git clone of GYP as follows:
git clone https://chromium.googlesource.com/external/gyp.git
cd gyp
GYP has a suite of tests which you can run with the provided test driver to make sure your changes aren't breaking anything important.
You run the test driver with e.g.
python gyptest.py
python gyptest.py test/win # Only run Windows-related tests.
python gyptest.py -a -f ninja # Only run ninja-related tests.
See Testing for more details on the test framework.
Note that it can be handy to look at the project files output by the tests to diagnose problems. The easiest way to do that is by kindly asking the test driver to leave the temporary directories it creates in-place. This is done by setting the enviroment variable "PRESERVE", e.g.
set PRESERVE=all # On Windows
export PRESERVE=all # On saner platforms.
All changes to GYP must be code reviewed before submission, GYP uses rietveld.
Upload your change with:
git cl upload
Once you're ready to submit, you can use the GYP try bots to test your change with e.g.
git try
Once the change has been approved (LGTMed) and passes trybots, you can submit it with:
git cl land
To be allowed to submit, you will need committer rights in the project. You need to do the new password dance at https://chromium.googlesource.com/new-password .
Remove the [svn] entry from .git/config, and the .git/svn subdirs to avoid
having git cl land complain that it looks like the repo is a SVN one. It might
be easier to just repull instead.