[Bug]: `pest-plugin-phpstan` Undefined variable: $this inside `->with` functions

[ayrtonandino]

What Happened

When using Pest’s ->with() dataset feature together with beforeEach to initialize $this properties, PHPStan (via pest-plugin-phpstan) incorrectly reports Undefined variable: $this inside the dataset closures.

 ------ ------------------------------------- 
  Line   PhpstanTest.php                      
 ------ ------------------------------------- 
  20     Undefined variable: $this            
         🪪  variable.undefined               
         ✏️  tests/Feature/PhpstanTest.php:20  
  21     Undefined variable: $this            
         🪪  variable.undefined               
         ✏️  tests/Feature/PhpstanTest.php:21  
 ------ -------------------------------------

How to Reproduce

In any Pest test file (e.g. tests/Feature/PhpstanTest.php):

<?php

declare(strict_types=1);

use function Pest\Laravel\postJson;

beforeEach(function (): void {
    $this->data = ['data1', 'data2'];
});

test('search', function (string $searchValue): void {
    postJson('/api/search', ['search' => $searchValue])->assertOk();
})->with([
    'data 1' => fn(): string => $this->data[0],
    'data 2' => fn(): string => $this->data[1],
]);

Run PHPStan analysis:

vendor/bin/phpstan analyze tests/Feature/PhpstanTest.php

Sample Repository

No response

Pest Version

5.0

PHP Version

8.4.16

Operation System

macOS, Windows, Linux

Notes

While this code runs perfectly fine at test runtime (Pest correctly binds $this to the test case context), PHPStan flags $this as Undefined variable

[ayrtonandino]

Pest.php

<?php

declare(strict_types=1);

use App\Enums\UserRoleEnum;
use App\Models\User;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Database\Eloquent\Factories\Factory;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Foundation\Testing\LazilyRefreshDatabase;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;
use Laravel\Sanctum\Sanctum;
use Pest\PendingCalls\TestCall;
use Pest\Support\HigherOrderTapProxy;
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;
use Tests\TestCase;

use function Pest\Laravel\freezeTime;

pest()
    ->extend(TestCase::class)
    ->beforeEach(fn(): mixed => freezeTime());

pest()
    ->use(LazilyRefreshDatabase::class)
    ->beforeEach(fn(): HigherOrderTapProxy|TestCall => actingAsAdmin())
    ->in('Feature');

function actingAsGuest(): HigherOrderTapProxy|TestCall
{
    Auth::forgetUser();

    return test();
}

function actingAsUser(User $user): HigherOrderTapProxy|TestCall
{
    Sanctum::actingAs($user, ['*']);

    return test();
}

function actingAsVendedor(): HigherOrderTapProxy|TestCall
{
    actingAsUser(User::query()->where('role', UserRoleEnum::VENDEDOR)->first());

    return test();
}

function actingAsAdmin(): HigherOrderTapProxy|TestCall
{
    actingAsUser(User::query()->where('role', UserRoleEnum::ADMIN)->first());

    return test();
}

// @note more functions i use to work with excel files

TestCase.php

<?php

declare(strict_types=1);

namespace Tests;

use Illuminate\Foundation\Testing\TestCase as BaseTestCase;

abstract class TestCase extends BaseTestCase
{
    protected bool $seed = true;
}