Laravel: test if your database migrations files contain a down-method

Here is a quick tip on how to test if your database migrations do not contain any down methods.

I've always filled my migrations with a `down` method in my projects. But since I saw this tweet from Aaron Francis, I stopped using this in my projects.

One of our internal rules is that we only ever migrate the database forward, never backwards. It ensures a more predictable state for our database.

Here is the test you can use in your projects:

<?php

use Illuminate\Database\Migrations\Migrator;
use Tests\TestCase;

class NoDownMigrationsTest extends TestCase
{
  /** @test */
  public function there_are_no_down_migrations()
  {
    /** @var Migrator $migrator */
    $migrator = app('migrator');

    $files = $migrator->getMigrationFiles([
      $this->app->databasePath() . DIRECTORY_SEPARATOR . 'migrations'
    ]);

    $migrator->requireFiles($files);

    foreach($files as $file) {
      $class = $migrator->resolve($migrator->getMigrationName($file));
      $reflector = new ReflectionClass($class);

      // We don't use down migrations because we don't want to ever run 
      // `down` in prod, it's too dangerous. If anything from an old
      // migration needs to be undone, create a new migration for it.
      $this->assertFalse(
        $reflector->hasMethod('down'),
        get_class($class) . ' migration has a down method. Please remove it.'
      );
    }
  }
}

Thanks Aaron for this quick tip!