feature #26803 [Messenger] Add debug:messenger CLI command (ro0NL, sroze)

This PR was merged into the 4.1 branch.

Discussion
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[Messenger] Add debug:messenger CLI command

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

Adds a `debug:messenger` CLI command to expose message classes that can be dispatched. Heavily inspired by `debug:autowiring`.

Commits
-------

7f87309c10 fix deps
290c7eb1bc Rename the command `DebugCommand`
9847b83723 [Messenger] Add debug:messenger CLI command

Author: sroze

Command/DebugCommand.php

@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Messenger\Command;
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+/**
+ * A console command to debug Messenger information.
+ *
+ * @author Roland Franssen <[email protected]>
+ *
+ * @experimental in 4.1
+ */
+class DebugCommand extends Command
+{
+    protected static $defaultName = 'debug:messenger';
+
+    private $mapping;
+
+    public function __construct(array $mapping)
+    {
+        parent::__construct();
+
+        $this->mapping = $mapping;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function configure()
+    {
+        $this
+            ->setDescription('Lists messages you can dispatch using the message bus')
+            ->setHelp(<<<'EOF'
+The <info>%command.name%</info> command displays all messages that can be
+dispatched using the message bus:
+
+  <info>php %command.full_name%</info>
+
+EOF
+            )
+        ;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $io = new SymfonyStyle($input, $output);
+        $io->title('Messenger');
+        $io->text('The following messages can be dispatched:');
+        $io->newLine();
+
+        $tableRows = array();
+        foreach ($this->mapping as $message => $handlers) {
+            $tableRows[] = array(sprintf('<fg=cyan>%s</fg=cyan>', $message));
+            foreach ($handlers as $handler) {
+                $tableRows[] = array(sprintf('    handled by %s', $handler));
+            }
+        }
+
+        if ($tableRows) {
+            $io->table(array(), $tableRows);
+        } else {
+            $io->text('No messages were found that have valid handlers.');
+        }
+    }
+}

DependencyInjection/MessengerPass.php

@@ -104,26 +104,29 @@ private function registerHandlers(ContainerBuilder $container)
         }
 
         $definitions = array();
+        $handlersLocatorMapping = array();
         foreach ($handlersByMessage as $message => $handlers) {
             if (1 === \count($handlers)) {
-                $handlersByMessage[$message] = current($handlers);
+                $handlersLocatorMapping['handler.'.$message] = current($handlers);
             } else {
                 $d = new Definition(ChainHandler::class, array($handlers));
                 $d->setPrivate(true);
                 $serviceId = hash('sha1', $message);
                 $definitions[$serviceId] = $d;
-                $handlersByMessage[$message] = new Reference($serviceId);
+                $handlersLocatorMapping['handler.'.$message] = new Reference($serviceId);
             }
         }
         $container->addDefinitions($definitions);
 
-        $handlersLocatorMapping = array();
-        foreach ($handlersByMessage as $message => $handler) {
-            $handlersLocatorMapping['handler.'.$message] = $handler;
-        }
-
         $handlerResolver = $container->getDefinition('messenger.handler_resolver');
         $handlerResolver->replaceArgument(0, ServiceLocatorTagPass::register($container, $handlersLocatorMapping));
+
+        if ($container->hasDefinition('console.command.messenger_debug')) {
+            $container->getDefinition('console.command.messenger_debug')
+                ->replaceArgument(0, array_map(function (array $handlers): array {
+                    return array_map('strval', $handlers);
+                }, $handlersByMessage));
+        }
     }
 
     private function guessHandledClasses(\ReflectionClass $handlerClass, string $serviceId): array