diff --git a/.cspell-project-words.txt b/.cspell-project-words.txt
new file mode 100644
index 0000000000000000000000000000000000000000..050badbb0d277d7ad672c95f2ae461d7887e88c5
--- /dev/null
+++ b/.cspell-project-words.txt
@@ -0,0 +1 @@
+texter
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000000000000000000000000000000000000..e82fb64da845b8f1e22003a363435953b203becb
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,14 @@
+include:
+ - project: $_GITLAB_TEMPLATES_REPO
+ file:
+ - '/includes/include.drupalci.main.yml'
+ - '/includes/include.drupalci.variables.yml'
+ - '/includes/include.drupalci.workflows.yml'
+
+variables:
+ OPT_IN_TEST_NEXT_MAJOR: '1'
+ OPT_IN_TEST_NEXT_MINOR: '1'
+ SKIP_ESLINT: '1'
+ _CURL_TEMPLATES_REF: 'main'
+ _TARGET_PHP: "8.4"
+ _CSPELL_IGNORE_PATHS: '"Makefile"'
diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000000000000000000000000000000000000..0daa0415013a5a1d51c593534bdc95d88a849b06
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,336 @@
+GNU General Public License
+==========================
+
+_Version 2, June 1991_
+_Copyright © 1989, 1991 Free Software Foundation, Inc.,_
+_51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA_
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+
+### Preamble
+
+The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.) You can apply it to
+your programs, too.
+
+When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+We protect your rights with two steps: **(1)** copyright the software, and
+**(2)** offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+The precise terms and conditions for copying, distribution and
+modification follow.
+
+### TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+**0.** This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The “Program”, below,
+refers to any such program or work, and a “work based on the Program”
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language. (Hereinafter, translation is included without limitation in
+the term “modification”.) Each licensee is addressed as “you”.
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope. The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+**1.** You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+**2.** You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+* **a)** You must cause the modified files to carry prominent notices
+stating that you changed the files and the date of any change.
+* **b)** You must cause any work that you distribute or publish, that in
+whole or in part contains or is derived from the Program or any
+part thereof, to be licensed as a whole at no charge to all third
+parties under the terms of this License.
+* **c)** If the modified program normally reads commands interactively
+when run, you must cause it, when started running for such
+interactive use in the most ordinary way, to print or display an
+announcement including an appropriate copyright notice and a
+notice that there is no warranty (or else, saying that you provide
+a warranty) and that users may redistribute the program under
+these conditions, and telling the user how to view a copy of this
+License. (Exception: if the Program itself is interactive but
+does not normally print such an announcement, your work based on
+the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole. If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works. But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+**3.** You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+* **a)** Accompany it with the complete corresponding machine-readable
+source code, which must be distributed under the terms of Sections
+1 and 2 above on a medium customarily used for software interchange; or,
+* **b)** Accompany it with a written offer, valid for at least three
+years, to give any third party, for a charge no more than your
+cost of physically performing source distribution, a complete
+machine-readable copy of the corresponding source code, to be
+distributed under the terms of Sections 1 and 2 above on a medium
+customarily used for software interchange; or,
+* **c)** Accompany it with the information you received as to the offer
+to distribute corresponding source code. (This alternative is
+allowed only for noncommercial distribution and only if you
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it. For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable. However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+**4.** You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+**5.** You are not required to accept this License, since you have not
+signed it. However, nothing else grants you permission to modify or
+distribute the Program or its derivative works. These actions are
+prohibited by law if you do not accept this License. Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+**6.** Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions. You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+**7.** If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all. For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices. Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+**8.** If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded. In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+**9.** The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Program
+specifies a version number of this License which applies to it and “any
+later version”, you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation. If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+**10.** If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission. For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this. Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+### NO WARRANTY
+
+**11.** BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+**12.** IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+END OF TERMS AND CONDITIONS
+
+### How to Apply These Terms to Your New Programs
+
+If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the “copyright” line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) <year> <name of author>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+ Gnomovision version 69, Copyright (C) year name of author
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w` and `show c` should show the appropriate
+parts of the General Public License. Of course, the commands you use may
+be called something other than `show w` and `show c`; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a “copyright disclaimer” for the program, if
+necessary. Here is a sample; alter the names:
+
+ Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ <signature of Ty Coon>, 1 April 1989
+ Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..501d43d6cf853ff5bbf20957ad44c5c53e2a49b7
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,22 @@
+phpstan-baseline:
+ php -d memory_limit=-1 ./vendor/bin/phpstan analyse --memory-limit=-1 --generate-baseline=./phpstan-baseline.neon --allow-empty-baseline
+
+phpcs:
+ vendor/bin/phpcs
+
+phpcbf:
+ vendor/bin/phpcbf
+
+phpstan:
+ php -d memory_limit=-1 ./vendor/bin/phpstan analyze
+
+lint: phpcs phpstan
+
+fix: phpcbf
+
+clean:
+ rm -rf vendor
+ rm -rf app
+ rm -rf modules
+ rm -rf core
+ rm -rf web
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000000000000000000000000000000000000..9a2bd9dca50401ae515272431cc59fcecf824368
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,36 @@
+{
+ "name": "drupal/notifier",
+ "description": "Integrates the Symfony Notifier component with Drupal. Provides the core of Notifier, without any channels.",
+ "type": "drupal-module",
+ "require": {
+ "php": ">=8.3",
+ "drupal/core": "^10.3 || ^11.0",
+ "symfony/notifier": "^6 || ^7"
+ },
+ "require-dev": {
+ "composer/installers": "^2",
+ "drupal/coder": "^8.3.25",
+ "drupal/core-dev": "^10.3 || ^11.0",
+ "phpstan/extension-installer": "^1.3",
+ "phpstan/phpstan": "^1.12.7",
+ "phpstan/phpstan-deprecation-rules": "*",
+ "phpstan/phpstan-phpunit": "^1.4 || ^2.0",
+ "phpstan/phpstan-strict-rules": "^1.5",
+ "previousnext/coding-standard": "^1"
+ },
+ "repositories": [
+ {
+ "type": "composer",
+ "url": "https://packages.drupal.org/8"
+ }
+ ],
+ "config": {
+ "allow-plugins": {
+ "composer/installers": true,
+ "php-http/discovery": true,
+ "phpstan/extension-installer": true,
+ "tbachert/spi": true,
+ "dealerdirect/phpcodesniffer-composer-installer": true
+ }
+ }
+}
diff --git a/notifier.info.yml b/notifier.info.yml
new file mode 100644
index 0000000000000000000000000000000000000000..54e6f2fdcadd065f5e0198b691179af509e347bf
--- /dev/null
+++ b/notifier.info.yml
@@ -0,0 +1,5 @@
+name: Notifier
+description: 'Integrates the Symfony Notifier component with Drupal. Provides the core of Notifier, without any channels.'
+type: module
+core_version_requirement: '>=11'
+php: 8.3
diff --git a/notifier.services.yml b/notifier.services.yml
new file mode 100644
index 0000000000000000000000000000000000000000..faf40764c4a294f4659f50ce1f7ed2ca9e8541b5
--- /dev/null
+++ b/notifier.services.yml
@@ -0,0 +1,33 @@
+parameters:
+ notifier.channel_policy:
+ # Keys: \Symfony\Component\Notifier\Notification\Notification::IMPORTANCE_*
+ # Values are arrays of strings.
+ urgent: []
+ high: []
+ medium: []
+ low: []
+ # Symfony Frameworks' `texter_transports` equivalent is `sms.transports` in sms.module.
+
+services:
+ _defaults:
+ public: false
+ autoconfigure: true
+ autowire: true
+
+ notifier:
+ class: Symfony\Component\Notifier\Notifier
+ arguments:
+ $channels: '!abstract "See NotifierCompilerPass"'
+ $policy: '@notifier.channel_policy'
+ Symfony\Component\Notifier\NotifierInterface: '@notifier'
+
+ notifier.channel_policy:
+ class: Symfony\Component\Notifier\Channel\ChannelPolicy
+ arguments:
+ $policy: '%notifier.channel_policy%'
+
+ notifier.transport_factory.abstract:
+ class: Symfony\Component\Notifier\Transport\AbstractTransportFactory
+ abstract: true
+ arguments:
+ $client: ~ # Symfony HTTP client isn't available. @fixme
diff --git a/phpcs.xml b/phpcs.xml
new file mode 100644
index 0000000000000000000000000000000000000000..1e63b05f2b1a6c549e310a5586794e953ff1b547
--- /dev/null
+++ b/phpcs.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ruleset>
+ <file>./src</file>
+ <file>./tests</file>
+
+ <rule ref="PreviousNextDrupal" />
+ <arg name="report" value="full"/>
+
+ <rule ref="Drupal.Commenting.ClassComment.Missing"><severity>0</severity></rule>
+ <rule ref="Drupal.Commenting.FunctionComment.Missing"><severity>0</severity></rule>
+</ruleset>
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000000000000000000000000000000000000..a5d20d994296226c85b4e5163111267bed7e8e80
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,14 @@
+parameters:
+ level: 9
+ paths:
+ - src
+ - tests
+ reportUnmatchedIgnoredErrors: true
+ treatPhpDocTypesAsCertain: false
+ fileExtensions:
+ - php
+ - module
+ - theme
+ - profile
+ - install
+ - inc
diff --git a/src/NotifierCompilerPass.php b/src/NotifierCompilerPass.php
new file mode 100644
index 0000000000000000000000000000000000000000..4fecdb8f1b3add9b8240ee1fc0abd53ec1b2fa21
--- /dev/null
+++ b/src/NotifierCompilerPass.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier;
+
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\Compiler\ServiceLocatorTagPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Notifier compiler pass.
+ */
+final class NotifierCompilerPass implements CompilerPassInterface {
+
+ public function process(ContainerBuilder $container): void {
+ // Do it here since Drupal's support for
+ // !tagged_locator('notifier.channel', 'channel') is wonky.
+ // vendor/symfony/framework-bundle/Resources/config/notifier.php:39.
+ $references = [];
+ foreach ($container->findTaggedServiceIds('notifier.channel') as $serviceId => $tags) {
+ // By 'channel'.
+ $channel = $tags[0]['channel'] ?? NULL;
+ if ($channel === NULL) {
+ throw new \LogicException('Notifier channel tag not found.');
+ }
+
+ $references[$channel] = new Reference($serviceId);
+ }
+
+ $container->getDefinition('notifier')
+ ->setArgument(0, ServiceLocatorTagPass::register($container, $references));
+ }
+
+}
diff --git a/src/NotifierServiceProvider.php b/src/NotifierServiceProvider.php
new file mode 100644
index 0000000000000000000000000000000000000000..c6674154c143d1519cfea513101d3535af78d59a
--- /dev/null
+++ b/src/NotifierServiceProvider.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\DependencyInjection\ServiceProviderInterface;
+
+/**
+ * Service provider for Notifier.
+ */
+final class NotifierServiceProvider implements ServiceProviderInterface {
+
+ public function register(ContainerBuilder $container): void {
+ $container
+ ->addCompilerPass(new NotifierCompilerPass());
+ }
+
+}
diff --git a/tests/modules/notifier_test/notifier_test.info.yml b/tests/modules/notifier_test/notifier_test.info.yml
new file mode 100644
index 0000000000000000000000000000000000000000..18e522d23ca19e7714ea46ac6017b2d06eee6a8a
--- /dev/null
+++ b/tests/modules/notifier_test/notifier_test.info.yml
@@ -0,0 +1,3 @@
+name: Notifier Test
+type: module
+package: Testing
diff --git a/tests/modules/notifier_test/notifier_test.services.yml b/tests/modules/notifier_test/notifier_test.services.yml
new file mode 100644
index 0000000000000000000000000000000000000000..938b59b38ac19695e1fd3a4cccfe9cce32a74f2c
--- /dev/null
+++ b/tests/modules/notifier_test/notifier_test.services.yml
@@ -0,0 +1,18 @@
+services:
+ _defaults:
+ autoconfigure: true
+ autowire: true
+
+ Drupal\notifier_test\Notifier\Channel\NotifierTestChannel:
+ arguments:
+ $transport: '@notifier_test.transports'
+ tags:
+ - { name: notifier.channel, channel: notifier_test_channel }
+
+ notifier_test.transports:
+ class: Symfony\Component\Notifier\Transport\Transports
+ arguments:
+ $transports: ['@Drupal\notifier_test\Notifier\Transport\NotifierTestTransport']
+
+ Drupal\notifier_test\Notifier\Transport\NotifierTestTransport: ~
+ Drupal\notifier_test\NotifierTestMessageBuffer: ~
diff --git a/tests/modules/notifier_test/src/Notifier/Channel/NotifierTestChannel.php b/tests/modules/notifier_test/src/Notifier/Channel/NotifierTestChannel.php
new file mode 100644
index 0000000000000000000000000000000000000000..5b7f7b555adc0f440b203263e7759d10abcf80d1
--- /dev/null
+++ b/tests/modules/notifier_test/src/Notifier/Channel/NotifierTestChannel.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test\Notifier\Channel;
+
+use Drupal\notifier_test\Notifier\Message\NotifierTestMessage;
+use Drupal\notifier_test\NotifierTestRecipientInterface;
+use Symfony\Component\Notifier\Channel\AbstractChannel;
+use Symfony\Component\Notifier\Notification\Notification;
+use Symfony\Component\Notifier\Recipient\RecipientInterface;
+
+final class NotifierTestChannel extends AbstractChannel {
+
+ public function supports(Notification $notification, RecipientInterface $recipient): bool {
+ return $recipient instanceof NotifierTestRecipientInterface;
+ }
+
+ public function notify(Notification $notification, RecipientInterface $recipient, ?string $transportName = NULL): void {
+ if (FALSE === $recipient instanceof NotifierTestRecipientInterface) {
+ // Impossible, validated by supports().
+ throw new \LogicException();
+ }
+
+ $message = NotifierTestMessage::fromNotification($notification, $recipient);
+
+ if (NULL !== $transportName) {
+ $message->transport($transportName);
+ }
+
+ $this->transport?->send($message);
+ }
+
+}
diff --git a/tests/modules/notifier_test/src/Notifier/Message/NotifierTestMessage.php b/tests/modules/notifier_test/src/Notifier/Message/NotifierTestMessage.php
new file mode 100644
index 0000000000000000000000000000000000000000..441397d56f028d69adfe419f8698d2286a01efd5
--- /dev/null
+++ b/tests/modules/notifier_test/src/Notifier/Message/NotifierTestMessage.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test\Notifier\Message;
+
+use Drupal\notifier_test\NotifierTestRecipientInterface;
+use Symfony\Component\Notifier\Message\MessageInterface;
+use Symfony\Component\Notifier\Message\MessageOptionsInterface;
+use Symfony\Component\Notifier\Notification\Notification;
+
+final class NotifierTestMessage implements MessageInterface {
+
+ private ?string $transport = NULL;
+
+ private function __construct(
+ public string $subject,
+ public string $toIdentifier,
+ ) {
+ }
+
+ public static function fromNotification(Notification $notification, NotifierTestRecipientInterface $recipient): self {
+ $message = new self(
+ subject: $notification->getSubject(),
+ toIdentifier: $recipient->getIdentifier(),
+ );
+ return $message;
+ }
+
+ /**
+ * @return $this
+ */
+ public function transport(?string $transport): static {
+ $this->transport = $transport;
+
+ return $this;
+ }
+
+ public function getRecipientId(): ?string {
+ return NULL;
+ }
+
+ public function getSubject(): string {
+ return $this->subject;
+ }
+
+ public function getOptions(): ?MessageOptionsInterface {
+ return NULL;
+ }
+
+ public function getTransport(): ?string {
+ return $this->transport;
+ }
+
+}
diff --git a/tests/modules/notifier_test/src/Notifier/Transport/NotifierTestTransport.php b/tests/modules/notifier_test/src/Notifier/Transport/NotifierTestTransport.php
new file mode 100644
index 0000000000000000000000000000000000000000..35ab65088195bab7597ec697734b2ff835e1a345
--- /dev/null
+++ b/tests/modules/notifier_test/src/Notifier/Transport/NotifierTestTransport.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test\Notifier\Transport;
+
+use Drupal\notifier_test\NotifierTestMessageBuffer;
+use Symfony\Component\Notifier\Message\MessageInterface;
+use Symfony\Component\Notifier\Message\SentMessage;
+use Symfony\Component\Notifier\Transport\TransportInterface;
+
+final class NotifierTestTransport implements TransportInterface {
+
+ public function __construct(
+ private NotifierTestMessageBuffer $buffer,
+ ) {
+ }
+
+ public function __toString(): string {
+ return 'notifier_test transport';
+ }
+
+ public function send(MessageInterface $message): ?SentMessage {
+ $this->buffer->push($message);
+
+ return new SentMessage($message, (string) $this);
+ }
+
+ public function supports(MessageInterface $message): bool {
+ return TRUE;
+ }
+
+}
diff --git a/tests/modules/notifier_test/src/NotifierTestMessageBuffer.php b/tests/modules/notifier_test/src/NotifierTestMessageBuffer.php
new file mode 100644
index 0000000000000000000000000000000000000000..082fff2b682598884575bd324bb6da89c0570da7
--- /dev/null
+++ b/tests/modules/notifier_test/src/NotifierTestMessageBuffer.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test;
+
+use Drupal\Core\State\StateInterface;
+use Symfony\Component\Notifier\Message\MessageInterface;
+
+final class NotifierTestMessageBuffer {
+
+
+ public const STATE = 'notifier_test_messages';
+
+ public function __construct(
+ private StateInterface $state,
+ ) {
+ }
+
+ public function push(MessageInterface $message): void {
+ /** @var \Symfony\Component\Notifier\Message\MessageInterface[] $buffer */
+ $buffer = $this->state->get(static::STATE, []);
+ $buffer[] = $message;
+ $this->state->set(static::STATE, $buffer);
+ }
+
+ /**
+ * @phpstan-return \Symfony\Component\Notifier\Message\MessageInterface[]
+ */
+ public function getAndClear(): array {
+ /** @var \Symfony\Component\Notifier\Message\MessageInterface[] $buffer */
+ $buffer = $this->state->get(static::STATE, []);
+ $this->state->delete(static::STATE);
+ return $buffer;
+ }
+
+}
diff --git a/tests/modules/notifier_test/src/NotifierTestRecipient.php b/tests/modules/notifier_test/src/NotifierTestRecipient.php
new file mode 100644
index 0000000000000000000000000000000000000000..c54a5b15e8b8ab4d6ace1c0f58e3bee877f6551b
--- /dev/null
+++ b/tests/modules/notifier_test/src/NotifierTestRecipient.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test;
+
+final class NotifierTestRecipient implements NotifierTestRecipientInterface {
+
+ public function __construct(
+ private readonly string $identifier,
+ ) {
+ }
+
+ public function getIdentifier(): string {
+ return $this->identifier;
+ }
+
+}
diff --git a/tests/modules/notifier_test/src/NotifierTestRecipientInterface.php b/tests/modules/notifier_test/src/NotifierTestRecipientInterface.php
new file mode 100644
index 0000000000000000000000000000000000000000..17a216a569861a70576aaf4ae40514c0446836f7
--- /dev/null
+++ b/tests/modules/notifier_test/src/NotifierTestRecipientInterface.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\notifier_test;
+
+use Symfony\Component\Notifier\Recipient\RecipientInterface;
+
+interface NotifierTestRecipientInterface extends RecipientInterface {
+
+ public function getIdentifier(): string;
+
+}
diff --git a/tests/src/Kernel/NotifierTest.php b/tests/src/Kernel/NotifierTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..6701564fadabc49989163c53acd73ae5cadd5543
--- /dev/null
+++ b/tests/src/Kernel/NotifierTest.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\notifier\Kernel;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\notifier_test\NotifierTestMessageBuffer;
+use Drupal\notifier_test\NotifierTestRecipient;
+use Symfony\Component\Notifier\Notification\Notification;
+use Symfony\Component\Notifier\NotifierInterface;
+
+final class NotifierTest extends KernelTestBase {
+
+ protected static $modules = [
+ 'notifier',
+ 'notifier_test',
+ ];
+
+ public function testNotifier(): void {
+ $recipient = new NotifierTestRecipient('user@example.com');
+
+ $notification = (new Notification())
+ ->subject('Test message');
+
+ static::notifier()->send($notification, $recipient);
+
+ /** @var \Drupal\notifier_test\Notifier\Message\NotifierTestMessage[] $buffer */
+ $buffer = static::buffer()->getAndClear();
+ static::assertCount(1, $buffer);
+ static::assertEquals('Test message', $buffer[0]->getSubject());
+ static::assertEquals('user@example.com', $buffer[0]->toIdentifier);
+ }
+
+ public function register(ContainerBuilder $container): void {
+ parent::register($container);
+
+ $container->setParameter('notifier.channel_policy', [
+ 'urgent' => ['notifier_test_channel'],
+ 'high' => ['notifier_test_channel'],
+ 'medium' => ['notifier_test_channel'],
+ 'low' => ['notifier_test_channel'],
+ ]);
+ }
+
+ private static function notifier(): NotifierInterface {
+ /** @var \Symfony\Component\Notifier\NotifierInterface */
+ return \Drupal::service(NotifierInterface::class);
+ }
+
+ private static function buffer(): NotifierTestMessageBuffer {
+ /** @var \Drupal\notifier_test\NotifierTestMessageBuffer */
+ return \Drupal::service(NotifierTestMessageBuffer::class);
+ }
+
+}