private function createAdminUser()
    {
        $user = factory(User::class)->create(
            [
            'firstName' => $this->ADMIN_FIRST_NAME,
            'lastName' => $this->ADMIN_LAST_NAME,
            'slug' => str_slug($this->ADMIN_FIRST_NAME.'-'.$this->ADMIN_LAST_NAME),
            'email' => $this->ADMIN_EMAIL,
            'password' => Hash::make($this->ADMIN_PASSWORD),
            'isActive' => true
            ]
        );

        // assign role
        $user->assignRoles(UserGroup::getAdminGroup()->groupID, true);
    }