Laravel Model Factory without connection to database

I would like to use Laravel's Model Factory in some PHPUnit tests. The only thing I want to do is make a Model instance without saving it to database.

Why the Model Factory needs connection to database? These tests must pass on CI environment without configured database.

When I create Model manually by new App\Model($dataArray), tests pass and the connection is not needed.

I am using Model Factory in other places, so I would like to reuse it in that tests, to avoid code duplication.

I am using MongoDB and jenssegers/laravel-mongodb library, but I am guessing that it has no matter - in pure Eloquent and e.g. MySQL database, the issue would be the same.

Test that works without database:

class ModelTransformerTest extends TestCase
{
    public function testTransformMinimalModelData()
    {
        $data = [
            '_id' => $faker->md5,
            'email' => $faker->email,
        ];

        $model = new App\Model($data);
        // […];
    }
}

My Model Factory

$factory->defineAs(Model::class, 'base', function ($faker) {
    return [
        '_id' => $faker->md5,
        'email' => $faker->email,
    ];
});

Test that needs database connection:

class ModelTransformerTest extends TestCase
{
    public function testTransformMinimalModelData()
    {
        $model = factory(App\Model::class, 'base')->make();
        // […];
    }
}

Full stack trace:

Error: Class 'MongoDB\Driver\Manager' not found

app\vendor\mongodb\mongodb\src\Client.php:56
app\vendor\jenssegers\mongodb\src\Jenssegers\Mongodb\Connection.php:147
app\vendor\jenssegers\mongodb\src\Jenssegers\Mongodb\Connection.php:37
app\vendor\jenssegers\mongodb\src\Jenssegers\Mongodb\MongodbServiceProvider.php:27
app\vendor\illuminate\database\DatabaseManager.php:173
app\vendor\illuminate\database\DatabaseManager.php:68
app\vendor\illuminate\database\Eloquent\Model.php:3282
app\vendor\illuminate\database\Eloquent\Model.php:3248
app\vendor\jenssegers\mongodb\src\Jenssegers\Mongodb\Eloquent\Model.php:523
app\vendor\jenssegers\mongodb\src\Jenssegers\Mongodb\Eloquent\Model.php:284
app\vendor\illuminate\database\Eloquent\Model.php:443
app\vendor\illuminate\database\Eloquent\Model.php:281
app\vendor\illuminate\database\Eloquent\FactoryBuilder.php:142
app\vendor\illuminate\database\Eloquent\Model.php:2286
app\vendor\illuminate\database\Eloquent\FactoryBuilder.php:143
app\vendor\illuminate\database\Eloquent\FactoryBuilder.php:106
app\tests\phpunit\Transformers\ModelTransformerTest.php:25
\php\pear\PHPUnit\TextUI\Command.php:176
\php\pear\PHPUnit\TextUI\Command.php:129