Use a stub log driver in your laravel tests

CreatesApplication.php

<?php

namespace Tests;

use Illuminate\Foundation\Application;
use Illuminate\Contracts\Console\Kernel;

trait CreatesApplication
{
    /**
     * @var \Illuminate\Log\Writer
     */
    protected $logWriter;

    public function createApplication()
    {
        // ...

        $this->disableLogWriter($app);

        return $app;
    }

    public function withLogWriter()
    {
        $this->app['log'] = $this->logWriter;
    }

    public function withoutLogWriter()
    {
        $this->app['log'] = new class {
            public function __call($method, $arguments)
            {
                //
            }
        };
    }

    protected function disableLogWriter(Application &$app)
    {
        $this->logWriter = $this->logWriter ?? $app['log'];

        $app['log'] = new class {
            public function __call($method, $arguments)
            {
                //
            }
        };
    }
}