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CI: switch to GitHub Actions - step 3: linting
This commit:
* Adds a GH Actions workflow for the PHP lint CI check.
* Removes all references to that action from the `.travis.yml` configuration.
* Add a "Build Status" badge in the Readme to use the results from the GH `Lint` Action runs.
* Adds two small tweaks to the `lint` script in the `composer.json`.
Notes:
1. Builds will run on:
- Select pushes using branch filtering similar to before.
- All pull requests.
- When manually triggered.
Note: manual triggering of builds has to be [explicitly allowed](https://github.blog/changelog/2020-07-06-github-actions-manual-triggers-with-workflow_dispatch/). This is not a feature which is enabled by default.
2. If a previous GH actions run for the same branch hadn't finished yet when the same branch is pushed again, the previous run will be cancelled.
In Travis, this was an option on the "Settings" page - "Auto cancellation" -, which was turned on for most, if not all, Yoast repos. The `concurrency` configuration in the GHA script emulates the same behaviour.
3. The default ini settings used by the `setup-php` action are based on the `php.ini-production` configuration.
This means that `error_reporting=E_ALL & ~E_DEPRECATED & ~E_STRICT`, `display_errors` is set to `Off` and `zend.assertions` is set to `-1` (= do not compile).
For the purposes of CI, especially for linting and testing code, I'd recommend running with `zend.assertions=-1`, `error_reporting=-1` and `display_errors=On` to ensure **all** PHP notices are shown.
Note: this only needs to be done for the PHP version used for the actual linting.
Note: the defaults will be changed in the next major of `setup-php` to be based on the `php.ini-develop` configuration, but that may still be a while off.
Refs:
* shivammathur/setup-php#450
* shivammathur/setup-php#469
4. As the prefixing of the dependencies needs a higher PHP version, the `setup-php` action is used twice within this workflow.
The first time, it sets up PHP 7.2 to allow for creating the `vendor_prefixed` directory.
The second time, it sets up the PHP version on which we want to do the actual linting.
Note: last time I checked, I found that within a workflow you can only switch PHP versions once, but that is sufficient for our purposes. (may have changed in the mean time)
5. As the `composer.lock` file for this plugin contains dependencies which are locked at versions which are incompatible with the full range of PHP versions supported by the plugin, we need to do some juggling to allow the linting to work (on all supported PHP versions).
Previously in Travis, an uncontrolled `composer update` would be run to get round this.
Uncontrolled updates are generally not a good idea in CI as you may end up with passing tests based on updated dependencies, while in reality things would fail.
So, for this workflow, I've chosen to approach this slightly differently (compared to Travis), but still tried to keep things as simple as possible.
- First a full install is done on PHP 7.2. This will generate the `vendor_prefixed` directory, as well as set up all dependencies.
- Next, the dependencies which are only needed for the prefixing are removed.
This will remove a couple of dependencies which would automatically be loaded by Composer on loading of the autoload file (due to the use of `autoload.files` in those dependencies) and would trigger a parse error on PHP < 7.2 as they contain non-cross-version compatible code.
- Now those incompatible dependencies are removed, we **_don't_** actually need to do a re-`install` of the dependencies on the target PHP version as all we'll be using is PHP-Parallel-Lint and PHP-Parallel-Lint is compatible with PHP 5.3 and higher, so the version installed on PHP 7.2 will work on all PHP versions on which we need to do the linting.
It may be a bit counter-intuitive to do it like that, but it works and keeps the workflow as simple as possible, while still achieving the goal of the workflow. And we also avoid the uncontrolled update.
6. While the `setup-php` action offers the ability to [install the PHAR file for Parallel Lint](https://github.com/shivammathur/setup-php#wrench-tools-support), I've elected not to use that option as it would mean that we would not be able to use the `composer lint` script in the workflow, which would mean that the CLI arguments would have to be duplicated between the `composer.json` file and the `lint.yml` file.
IMO, that would make this a typical point of failure where updates would be done in one, but not the other.
If, at some point in the future, the Parallel Lint tool would start to support a config file for the CLI arguments, removing this point of failure, this choice can be (and should be) revisited.
7. Composer dependency downloads will be cached for faster builds using a [predefined GH action](https://github.com/marketplace/actions/install-composer-dependencies) specifically created for this purpose.
The alternative would be to handle the caching manually, which would add three extra steps to the script.
Note: Caching works differently between Travis and GH Actions.
On GH Actions, once a cache has been created, it can't be updated. It can only be replaced by a new cache with a different key.
As the PHP version, the `composer.json` and a potential `composer.lock` hash are all part of the key used by the above mentioned action, this difference should not have a significant impact.
Ref: https://docs.github.com/en/actions/advanced-guides/caching-dependencies-to-speed-up-workflows
8. The Linting check will display the results inline in the GitHub code view using the [cs2pr](https://github.com/staabm/annotate-pull-request-from-checkstyle) tool.
Differences with the Travis implementation:
* There is a minor difference in the branch filtering being done for `push` events.
Travis accepted PCRE regexes for the filtering. GH Actions uses glob patterns. The glob patterns now in place match the regexes as closely as possible, but are not an exact match to the "old" patterns. They should be sufficient for our purposes though.
* The tag-based branch filter has not been added as that filter was only intended for use with the `deploy` stage.
* Linting will now also be executed against PHP 8.1 and 8.2 (nightly).
Linting runs against PHP 8.2 will be "allowed to fail" for the time being.
Note: if any of the "allowed to fail" jobs actually fail, the workflow will show as successful, but there will still be a red `x` next to a PR.
This is a known issue in GHA: https://github.com/actions/toolkit/issues/399
There are work-arounds possible for this, however, the work-arounds would hide failures even more, meaning that chances are they won't be seen until they actually become a problem (no longer allowed to fail), which is too late.
Regarding the changes to the Composer `lint` scripts:
* For the generic `lint` command, the `vendor_prefixed` directory is no longer excluded from the linting as the adjusted code **does** need to be cross-version compatible and safeguarding that PHP_Scoper doesn't introduce cross-version compatibility issues is a good thing.- Loading branch information
