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Vendoring Puppeteer
===================
As mentioned in the chapter on [Testing], we run the full [Puppeteer
test suite] on try. These tests are vendored in central under
_remote/test/puppeteer/_ and we have a script to pull in upstream changes.
We periodically perform a manual two-way sync. Below is an outline of the
process interspersed with some tips.
1. Clone the Puppeteer git repository and checkout the release tag you want
to vendor into mozilla-central.
% git checkout tags/v10.0 -b sync-v10.0
2. Apply any recent changes in `remote/test/puppeteer` to the Puppeteer branch
created above.
You might want to [install the project] at this point and make sure unit
tests pass. Check the project's `package.json` for relevant testing commands.
You should use this as basis for a PR to the Puppeteer project once you are
satisfied that the two-way sync will be successful in mozilla-central. See
their [CONTRIBUTING.md].
Typically, the changes we push to Puppeteer include unskipping newly passing
unit tests for Firefox along with minor fixes to the tests or
to Firefox-specific browser-fetching and launch code.
Be sure to [run tests against both Chromium and Firefox] in the Puppeteer
repo. You can specify your local Firefox build when you do so:
% BINARY=<path-to-objdir-binary> npm run funit
3. Now back in mozilla-central, you can run the following mach command to
copy over the Puppeteer branch you just prepared. The mach command has
flags to specify a local or remote repository as well as a commit.
% ./mach remote vendor-puppeteer
By default, this command also installs the newly-pulled Puppeteer package
in order to generate a new `package-lock.json` file for the purpose of
pinning Puppeteer dependencies for our CI. There is a `--no-install` option
if you want to skip this step; for example, if you want to run installation
separately at a later point.
4. Go through the changes under `remote/test/puppeteer/test` and [unskip] any
newly-skipped tests (e.g. change `itFailsFirefox` to `it`).
A mass-change with `awk` might be useful here.
Why do we do this? The Puppeteer team runs their unit tests against Firefox
in their CI with many tests skipped. In contrast, we leave these tests
unskipped in Mozilla CI and track test expectation metadata
in [puppeteer-expected.json] instead.
5. Use `./mach puppeteer-test` (see [Testing]) to run Puppeteer tests against
both Chromium and Firefox in headless mode. Again, only running a subset of
tests against Firefox is fine -- at this point you just want to check that
the typescript compiles and the browser binaries are launched successfully.
6. Next you want to update the test expectation metadata: test results might
have changed, tests may have been renamed, removed or added. The
easiest way to do this is to run the Puppeteer test job on try
(see [Testing]). You will find the new test metadata as an artifact on that
job and you can copy it over into your sync patch if it looks reasonable.
Examine the job logs and makes sure the run didn't get interrupted early
by a crash or a hang, especially if you see a lot of
`TEST-UNEXPECTED-MISSING` in the Treeherder Failure Summary. You might need
to add new test skips or fix some new bug in the unit tests. This is the
fun part.
7. Once you are happy with the metadata and are ready to submit the sync patch
up for review, run the Puppeteer test job on try again with `--rebuild 10`
to check for stability.
[Testing]: ./Testing.html