Laravel ReplaceTestVars Middleware - seen here: https://laracasts.com/discuss/channels/testing/l5-phpunit-testing-the-post-request-with-csrf

ReplaceTestVars.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Contracts\Routing\Middleware;
use Illuminate\Contracts\Foundation\Application;

class ReplaceTestVars implements Middleware
{

    /**
     * The application implementation.
     *
     * @var Application
     */
    protected $app;

    /**
     * Create a new filter instance.
     *
     * @param Application $app
     *
     * @return \App\Http\Middleware\ReplaceTestVars
     */
    public function __construct(Application $app)
    {
        $this->app = $app;
    }

    /**
     * Handle an incoming request.
     *
     * @param \Illuminate\Http\Request $request
     * @param \Closure                 $next
     *
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        if ('testing' === $this->app->environment() && ($request->isMethod('post') || $request->isMethod('put')) ) {
            $input = $request->all();
            $input['_token'] = $request->session()->token();
            $request->replace($input);
        }
        return $next($request);
    }
}