Add support for --complete

When using orm:schema-tool:update together with --complete, all assets
not described by the current metadata is dropped.

This is an issue when using doctrine/migrations, because not using that
option is deprecated, and because when it is used, the table that holds
the migrations is dropped as well since it is not described by ORM
metadata.

A solution to that is configuring an asset filter that filters out the
metadata table except when running commands inside the migrations
namespace.

EventListener/SchemaFilterListener.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Bundle\MigrationsBundle\EventListener;
+
+use Doctrine\DBAL\Schema\AbstractAsset;
+use Doctrine\Migrations\Metadata\Storage\TableMetadataStorageConfiguration;
+use Doctrine\Migrations\Tools\Console\Command\DoctrineCommand;
+use Symfony\Component\Console\Event\ConsoleCommandEvent;
+
+/**
+ * Acts as a schema filter able that hides the migration metadata table except
+ * when the execution context is that of command inside the migrations
+ * namespace.
+ */
+final class SchemaFilterListener
+{
+    /** @var bool */
+    private $enabled = true;
+
+    /** @param AbstractAsset|string $asset */
+    public function __invoke($asset): bool
+    {
+        if (! $this->enabled) {
+            return true;
+        }
+
+        if ($asset instanceof AbstractAsset) {
+            $asset = $asset->getName();
+        }
+
+        return $asset !== (new TableMetadataStorageConfiguration())->getTableName();
+    }
+
+    public function disable(): void
+    {
+        $this->enabled = false;
+    }
+
+    public function onConsoleCommand(ConsoleCommandEvent $event): void
+    {
+        $command = $event->getCommand();
+
+        if (! $command instanceof DoctrineCommand) {
+            return;
+        }
+
+        $this->disable();
+    }
+}

Resources/config/services.xml

@@ -146,6 +146,11 @@
             <tag name="console.command" command="doctrine:migrations:version" />
         </service>
 
+        <service id="doctrine_migrations.schema_filter_listener" class="Doctrine\Migrations\EventListener\SchemaFilterListener">
+            <tag name="kernel.event_listener" event="console.command" method="onConsoleCommand" />
+            <tag name="doctrine.dbal.schema_filter" />
+        </service>
+
     </services>
 
 </container>

Tests/Collector/EventListener/SchemaFilterListenerTest.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Bundle\MigrationsBundle\Tests\Collector\EventListener;
+
+use Doctrine\Bundle\MigrationsBundle\EventListener\SchemaFilterListener;
+use Doctrine\DBAL\Schema\Table;
+use Doctrine\Migrations\Tools\Console\Command\DoctrineCommand;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Event\ConsoleCommandEvent;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Output\NullOutput;
+
+class SchemaFilterListenerTest extends TestCase
+{
+    public function testItFiltersOutMigrationMetadataTableByDefault(): void
+    {
+        $listener = new SchemaFilterListener();
+
+        self::assertFalse($listener(new Table('doctrine_migration_versions')));
+        self::assertTrue($listener(new Table('some_other_table')));
+    }
+
+    public function testItFiltersNothingWhenDisabled(): void
+    {
+        $listener = new SchemaFilterListener();
+        $listener->disable();
+
+        self::assertTrue($listener(new Table('doctrine_migration_versions')));
+        self::assertTrue($listener(new Table('some_other_table')));
+    }
+
+    public function testItDisablesItselfWhenTheCurrentCommandIsAMigrationsCommand(): void
+    {
+        $listener          = new SchemaFilterListener();
+        $migrationsCommand = new class extends DoctrineCommand {
+        };
+
+        $listener->onConsoleCommand(new ConsoleCommandEvent(
+            $migrationsCommand,
+            new ArrayInput([]),
+            new NullOutput()
+        ));
+
+        self::assertTrue($listener(new Table('doctrine_migration_versions')));
+    }
+}