Laravel Eloquent integration test model save with DB

User.php

<?php

namespace App\Models;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Support\Facades\Hash;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name',
        'email',
        'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password',
        'remember_token',
    ];

    /**
     * The attributes that should be cast to native types.
     *
     * @var array
     */
    protected $casts = [
        'email_verified_at' => 'datetime',
    ];

    public function hasVerifiedEmail()
    {
        return !is_null($this->email_verified_at);
    }
}

UserService.php

<?php

namespace App\Services\Web;

use App\Models\User;

class UserService
{
    public function verifyUser($user)
    {
        $user->email_verified_at = now();

        return $user->save() ? $user : false;
    }
}

UserServiceTest.php

<?php

namespace Tests\Feature\Service\Web;

use Tests\TestCase;
use Illuminate\Foundation\Testing\DatabaseTransactions;
use App\Services\Web\UserService;
use App\Models\User;

class UserServiceTest extends TestCase
{
    use DatabaseTransactions;

    public function testItReturnUserWhenVerifySuccess()
    {
        $notVerifiedUser = factory(User::class)->create([
            'email_verified_at' => null,
        ]);

        $result = (new UserService)->verifyUser($notVerifiedUser);
        // Re-get from DB to check it is saved or not
        $notVerifiedUser->refresh();

        $this->assertTrue($result);
        $this->assertTrue($notVerifiedUser->hasVerifiedEmail());
    }

    public function testItReturnFalseWhenVerifyUserFailed()
    {
        $notVerifiedUser = factory(User::class)->create([
            'email_verified_at' => null,
        ]);
        // Prevent model saving?
        User::saving(function () {
            return false;
        });

        $result = (new UserService)->verifyUser($notVerifiedUser);
        // Re-get from DB to check it is saved or not
        $notVerifiedUser->refresh();

        $this->assertFalse($result);
        $this->assertFalse($notVerifiedUser->hasVerifiedEmail());
    }
}