Use Laravel's Artisan to set the fixtures for your tests

AbstractBehatContex.php

class AbstractBehatContext extends MinkContext {

    /**
     * Slight hack to put beforeSuite code into beforeScenario
     * @var bool
     */
    protected static $databaseReady = false;

    /**
     * @BeforeScenario
     */
    public function setupDatabase() {
    
        // Check if we already did this
        if(!self::$databaseReady) {
        
            // Find the host
            $baseUrl = $this->getMinkParameter('base_url');
            $urlParts = parse_url($baseUrl);
            $_SERVER['HTTP_HOST'] = $urlParts['host'];

            // Now call start.php
            require_once 'bootstrap/start.php';

            // Call Artisan
            Artisan::call(
                'migrate:refresh',
                [
                    '--seed' => true,
                ]
            );

            // Flag this as done
            self::$databaseReady = true;
        }
        
    }
    
}