php_laravel_laracasts/database/factories/ModelFactory.php

<?php

/*
|--------------------------------------------------------------------------
| Model Factories
|--------------------------------------------------------------------------
|
| Here you may define all of your model factories. Model factories give
| you a convenient way to create models for testing and seeding your
| database. Just tell the factory how a default model should look.
|
| "A blueprint for an Eloquent model".
|
*/

/** @var \Illuminate\Database\Eloquent\Factory $factory */

use App\Post;
use App\User;
use Faker\Generator;

$factory->define(User::class, function (Generator $faker) {
    static $password;

    return [
        'name' => $faker->name,
        'email' => $faker->unique()->safeEmail,
        'password' => $password ?: $password = bcrypt('secret'),
        'remember_token' => str_random(10),
    ];
});

$factory->define(Post::class, function (Generator $faker) {
   return [
       'user_id' => function () {
            return factory(User::class)->create()->id;
       },
       'title' => $faker->sentence,
       'body' => $faker->paragraph,
   ];
});