crater/app/Mail/TestMail.php

<?php
namespace Crater\Mail;

use Illuminate\Bus\Queueable;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Contracts\Queue\ShouldQueue;

class TestMail extends Mailable
{
    use Queueable, SerializesModels;
    public $subject;
    public $message;

    /**
     * Create a new message instance.
     *
     * @param $subject
     * @param $message
     */
    public function __construct($subject, $message)
    {
        $this->subject = $subject;
        $this->message = $message;
    }

    /**
     * Build the message.
     *
     * @return $this
     */
    public function build()
    {
        return $this->subject($this->subject)->markdown('emails.test')->with([
            'my_message' => $this->message
        ]);
    }
}