Drupal Core Development Composer Project
This is a Composer project template for developing Drupal core.
It allows:
- a clean git clone of Drupal core.
- Composer dependencies of Drupal core are installed, so Drupal can be installed and run as normal.
- other Composer packages you might want, such as Drush, Devel module, and Admin Toolbar module, can be installed too, but don't affect the composer files that are part of Drupal core.
Installation
To install a Drupal project for working on Drupal core:
$ composer create-project joachim-n/drupal-core-development-project
Composer will clone Drupal core into a 'repos/drupal' directory within the project, and then symlink that into the project when it installs Drupal core.
Once the installation is complete, you can install Drupal as normal, either with drush si or with the web UI.
Limitations
Most Drush commands work, but drush cr does not. To rebuild the Drupal container and clear caches, install Devel module and use its menu items instead.
A fix is being worked on: see https://www.drupal.org/project/drupal/issues/1792310.
Developing Drupal core
You can use the Drupal core git clone at 'repos/drupal/' in any way you like: create feature branches, clone from drupal.org issue forks, and so on. Changes you make to files in the git clone affect the project, since the git clone is symlinked into it.
Managing the Composer project
You can install any Composer packages you like, including Drupal contrib modules, without affecting the git clone of Drupal core. To work with Composer, you need to be in the root directory of the project.
Changes to the git clone's composer.json will be taken into account by Composer. So for example, if pulling from the main branch of Drupal core changes Composer dependencies, you should run Composer on the project to install these.
Running tests
The following are required to run tests.
PHPUnit configuration
The simplest way to run tests with this setup is to put the phpunit.xml file in the project root and then run tests from there:
$ vendor/bin/phpunit web/core/PATH-TO-TEST-FILE/TestFile.php
To set this up, copy Drupal core's sample phpunit.xml file to the project root:
$ cp web/core/phpunit.xml.dist phpunit.xml
Then change the bootstrap attribute so the path is correct:
Technical details
The rest of this document is gory technical details you only need to know if you're working on this project template or debugging it.
How it works
The composer.json at the project root uses a Composer path repository so that when the drupal/drupal package is installed, it's symlinked in from the Drupal core git clone, at the branch that the clone has checked out.
Drupal core itself defines path repositories in its top-level composer.json. These need to be overridden in the project root composer.json so they point to inside the Drupal core git clone.
Manual Installation
Clone the repository for this template into, say, 'drupal-dev'.
$ cd drupal-dev
# Create a folder in which to store git clones, which Composer will symlink in.
$ mkdir repos
$ cd repos
# Clone Drupal core, to whatever branch you like.
$ git clone --branch 9.2.x https://git.drupalcode.org/project/drupal.git
# Go back to the project root.
$ cd ..
# Install packages with Composer.
$ composer install
The Drupal core git clone will be clean apart from:
sites/default/settings.php
vendor
Since it doesn't have a .gitignore at the top level, you can add one to ignore those files if you like.
Project template development installation
To test how Composer creates a new project from the template, you need a git clone of the template repository.
In a separate location, do:
$ composer create-project joachim-n/drupal-core-development-project NEW_PROJECT_DIRECTORY --stability=dev --repository='{"url": "/path/to/git/clone/of/project/template/", "type": "vcs"}'
Workarounds
Several workarounds are necessary to make Drupal core work correctly when symlinked into the project. These are all taken care of by Composer scripts during installation. Details are below.
Vendor folder
The vendor folder has to be symlinked into the Drupal core repository, because otherwise code in core that expects to find a Composer autoloader fails.
This is done by a Composer script after initial installation. The manual command is:
ln -s ../../vendor ./repos/drupal/vendor
App root index.php patch
The index.php scaffold file has to be patched after it has been copied to web/index.php, because otherwise DrupalKernel guesses the Drupal app root as incorrectly being inside the Drupal core git clone, which means it can't find the settings.php file.
This is done by a Composer script after initial installation. The manual command is:
cd web && patch -p1 <../scaffold/scaffold-patch-index-php.patch
See https://www.drupal.org/project/drupal/issues/3188703 for more detail.
Simpletest folder
When running browser tests, the initial setup of Drupal in FunctionalTestSetupTrait::prepareEnvironment() creates a site folder using the real file locations with symlinks resolved, thus repos/drupal/sites/simpletest, but during the request to the test site, Drupal looks in /web/sites/simpletest.
Additionally, the HTML files output from Browser tests are written into the Drupal core git clone, and so the URLs shown in PHPUnit output are incorrect.
The fix for both of these is to create the simpletest site folder in the web root and symlink it into the Drupal core git clone.
This is done by a Composer script after initial installation. The manual command is:
mkdir -p web/sites/simpletest
ln -s ../../../web/sites/simpletest repos/drupal/sites
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