Laravel Model Factories ID not set - php

Question

I have a regular User model. The system works fine when I use it. But now I am trying to create unit tests in the PHPUnit that integrated with Laravel.
I have a factory that creates a user:
$factory->define(App\User::class, function (Faker\Generator $faker) {
return [
'id' => $faker->randomNumber(9),
'email' => $faker->safeEmail,
'first_name' => $faker->firstNameMale,
'last_name' => $faker->lastName,
'password' => bcrypt(str_random(10)),
'remember_token' => str_random(10),
];
});
I changed the User to have integer ID as the primary key but it not defined as auto-increment.
So the factory create random number for the ID.
Also I have created the simple test:
public function test_id_is_visible() {
$user = factory(App\User::class)->create();
$this->actingAs($user);
$this->visit('/userprofile');
$this->see($user->id);
}
That test always fails, but it seems to be OK when I navigate to the page manually.
I have noticed that in the test the $user->id is always 0. Even it can't be 0 in the factory. I checked and Laravel insert the user correctly to the database and it have correct ID, but in the code I always get 0.
What can I do to get the correct value of the ID?
EDIT
Now I see that if I changes $user = factory(App\User::class)->create(); to $user = factory(App\User::class)->make(); the user instance holds a correct ID. But why create clears the ID?

Answer 1

Update for Laravel 5.8+ Make sure to set
public $incrementing = false;
on your model.

Answer 2

The problem happened because the ID is not defined as auto-increment.
More information you can found in:
https://stackoverflow.com/a/31350800/1725836
Even the question is for Laravel 4 it is still relevant for Laravel 5.2.

Answer 3

You can write your tests like this:
$users = factory(User::class, 5)->make();
$users->each(function ($item, $key) {
$item->id = ++$key;
});
Now each user will have an id, without the need to persist the models to database (using create() instead of make()).
public function test_id_is_visible() {
$user = factory(App\User::class)->make();
$user->id = 7;
$this->actingAs($user);
$this->visit('/userprofile');
$this->see($user->id);
}