Use isReadonly() method to detect that driver is readonly; add test

src/Migrator.php

@@ -319,7 +319,7 @@ private function getDatabases(): iterable
         if ($this->dbal instanceof DatabaseManager) {
             return array_filter(
                 $this->dbal->getDatabases(),
-                fn (DatabaseInterface $db): bool => !$db->getDriver()->getSchemaHandler() instanceof ReadonlyHandler
+                fn (DatabaseInterface $db): bool => !$db->getDriver()->isReadonly()
             );
         }
         return [];

tests/Migrations/Unit/IsolatedMigratorTest.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Cycle\Migrations\Tests\Unit;
+
+use Cycle\Database\Config\DatabaseConfig;
+use Cycle\Database\Database;
+use Cycle\Database\DatabaseManager;
+use Cycle\Database\Driver\DriverInterface;
+use Cycle\Migrations\Config\MigrationConfig;
+use Cycle\Migrations\Migrator;
+use Cycle\Migrations\RepositoryInterface;
+use PHPUnit\Framework\TestCase;
+
+final class IsolatedMigratorTest extends TestCase
+{
+    public function testReadonlyDriversMustNotBeUsed()
+    {
+        $dbal = new DatabaseManager(new DatabaseConfig());
+        $dbal->addDatabase(
+            new Database(
+                'foo',
+                '',
+                $driver = $this->createMock(DriverInterface::class),
+            ),
+        );
+        $driver->expects($this->atLeastOnce())->method('isReadonly')->willReturn(true);
+        $driver
+            ->expects($this->any())
+            ->method($this->callback(fn($name) => $name !== 'isReadonly'))
+            ->willThrowException(new \RuntimeException('Unexpected method call'));
+
+        $repository = $this->createMock(RepositoryInterface::class);
+
+        $migrator = new Migrator(
+            new MigrationConfig([]),
+            $dbal,
+            $repository,
+        );
+
+        $migrator->isConfigured();
+    }
+}