Is there a way to test effect of several concurrent requests?

[mityukov]

Hi,

I'm trying to write a test that may recreate a race condition and test how the app behaves in this situation.

Example:

test('it behaves', function () {
    $slot = Slot::factory()->create(['remaining' => 1]);

    $s = new SlotService;
    $hold1 = $s->createHold($slot);
    $hold2 = $s->createHold($slot);

    // here I run `$s->confirmHold($hold1)` and  `$s->confirmHold($hold2)` in parallel

    // here I assert only one of those holds was actually confirmed.
});

I've tried doing so by using Concurrency::run(), Http::pool() and even with nunomaduro/pokio, but nothing worked.
The main issue, If I remember correctly, was that in each of those processes I had like a separate copy of database (in each, slot.remaining was equal 1 and no locks encountered).

What would be the proper way to test handling of race conditions in Laravel?