protected static function defaults(): array
    {
        return [
            'processes' => 'auto',
            'path' => '',
            'phpunit' => static::phpunit(),
            'functional' => false,
            'stop-on-failure' => false,
            'runner' => 'Runner',
            'no-test-tokens' => false,
            'colors' => false,
            'testsuite' => '',
            'max-batch-size' => 0,
            'filter' => null,
            'parallel-suite' => false,
            'passthru' => null,
            'passthru-php' => null,
            'verbose' => 0,
        ];
    }