Test pulling pending tenants concurrently

tests/Etc/pull-worker.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Worker for the "concurrent pulls" tests.
+ * Separate OS process that boots the same test env and calls pullPendingFromPool().
+ * Since multiple processes run at once, they race for the pool.
+ *
+ * Used like `php pull-worker.php <startAtUnixFloat> <firstOrCreate:0|1>`
+ *
+ * Outputs the key of the pulled tenant, or "null" if nothing was pulled.
+ */
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+use Stancl\Tenancy\Tests\Etc\Tenant;
+use Stancl\Tenancy\Tests\TestCase;
+
+$startAt = (float) ($argv[1] ?? 0);
+$firstOrCreate = ($argv[2] ?? '0') === '1';
+
+// createApplication() replays the suite's central-MySQL config without running setUp(),
+// so the pending tenants the parent test created survive into this process.
+(new class('pull-worker') extends TestCase {})->createApplication();
+
+// Wait so that every worker pulls at the same time
+if ($startAt > 0.0) {
+    time_sleep_until($startAt);
+}
+
+$tenant = Tenant::pullPendingFromPool($firstOrCreate);
+
+fwrite(STDOUT, $tenant?->getKey() ?? 'null');

tests/PendingTenantsTest.php

@@ -5,6 +5,7 @@ declare(strict_types=1);
 use Illuminate\Database\QueryException;
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Support\Facades\Artisan;
+use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Event;
 use Illuminate\Support\Facades\Schema;
 use Illuminate\Support\Str;
@@ -28,6 +29,7 @@ use Stancl\Tenancy\Events\TenancyInitialized;
 use Stancl\Tenancy\Listeners\BootstrapTenancy;
 use Stancl\Tenancy\Events\TenancyEnded;
 use Stancl\Tenancy\Listeners\RevertToCentralContext;
+use Symfony\Component\Process\Process;
 
 beforeEach($cleanup = function () {
     Tenant::$extraCustomColumns = [];
@@ -126,6 +128,82 @@ test('a new tenant gets created while pulling a pending tenant if the pending po
     expect(Tenant::withPending()->get()->count())->toBe(1); // All tenants
 });
 
+/**
+ * Spawn $count separate PHP processes that all call pullPendingFromPool() at the same
+ * time and return the keys of pulled tenants to simulate concurrent pulls.
+ *
+ * @see tests/Etc/pull-worker.php
+ */
+function runConcurrentPulls(int $count, bool $firstOrCreate = false): array
+{
+    $worker = __DIR__ . '/Etc/pull-worker.php';
+
+    // Shared start instant
+    $startAt = (string) (microtime(true) + 3.0);
+
+    /** @var Process[] $processes */
+    $processes = [];
+
+    for ($i = 0; $i < $count; $i++) {
+        $process = new Process(
+            ['php', $worker, $startAt, $firstOrCreate ? '1' : '0']
+        );
+        $process->start();
+        $processes[] = $process;
+    }
+
+    $pulledTenants = [];
+
+    foreach ($processes as $process) {
+        $process->wait();
+
+        expect($process->isSuccessful())->toBeTrue($process->getErrorOutput());
+
+        $output = trim($process->getOutput());
+
+        if ($output !== 'null' && $output !== '') {
+            // If a tenant was pulled, add its key to the results
+            $pulledTenants[] = $output;
+        }
+    }
+
+    return $pulledTenants;
+}
+
+test('concurrent pulls each claim a distinct pending tenant', function (bool $firstOrCreate) {
+    Tenant::createPending();
+    Tenant::createPending();
+    Tenant::createPending();
+
+    expect(Tenant::onlyPending()->count())->toBe(3);
+
+    runConcurrentPulls(8, $firstOrCreate);
+
+    expect(Tenant::onlyPending()->count())->toBe(0);
+    expect(Tenant::withoutPending()->count())->toBe($firstOrCreate ? 8 : 3);
+})->with([
+    'pull pending' => false,
+    'pull pending or create' => true,
+]);
+
+test('a failed attribute write rolls back the claim and leaves the tenant pending', function () {
+    // The claim and the attribute write share one transaction, so if applying the attributes
+    // fails the claim must roll back and the tenant must stay in the pool.
+    Schema::table('tenants', function (Blueprint $table) {
+        $table->string('slug')->nullable()->unique();
+    });
+
+    Tenant::$extraCustomColumns = ['slug'];
+
+    Tenant::create(['slug' => 'taken']);
+    Tenant::createPending();
+
+    expect(fn () => Tenant::pullPendingFromPool(false, ['slug' => 'taken']))
+        ->toThrow(QueryException::class);
+
+    expect(Tenant::onlyPending()->count())->toBe(1);
+});
+
 test('withoutPending chained with where clauses returns correct results', function () {
     $tenant = Tenant::create();
     $pendingTenant = Tenant::createPending();