Add basic unit test

.gitignore

@@ -1,2 +1,3 @@
 /vendor/
 composer.lock
+/.phpunit.result.cache

composer.json

@@ -18,6 +18,11 @@
             "Webgriffe\\PayumLockRequestExtension\\": "src/"
         }
     },
+    "autoload-dev": {
+        "psr-4": {
+            "Tests\\Webgriffe\\PayumLockRequestExtension\\": "tests/"
+        }
+    },
     "authors": [
         {
             "name": "Webgriffe SRL",

tests/InMemoryStore.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Webgriffe\PayumLockRequestExtension;
+
+use Symfony\Component\Lock\Key;
+use Symfony\Component\Lock\PersistingStoreInterface;
+
+final class InMemoryStore implements PersistingStoreInterface
+{
+    public function __construct(
+        public array $locks = [],
+    ) {
+    }
+
+    public function save(Key $key): void
+    {
+        $this->locks[(string) $key] = $key;
+    }
+
+    public function delete(Key $key): void
+    {
+        unset($this->locks[(string) $key]);
+    }
+
+    public function exists(Key $key): bool
+    {
+        return array_key_exists((string) $key, $this->locks);
+    }
+
+    public function putOffExpiration(Key $key, float $ttl): void
+    {
+        // do nothing, memory locks forever.
+    }
+}

tests/LockRequestExtensionTest.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Webgriffe\PayumLockRequestExtension;
+
+use Payum\Core\Extension\Context;
+use Payum\Core\Gateway;
+use Payum\Core\Model\Identity;
+use Payum\Core\Model\Token;
+use Payum\Core\Request\Capture;
+use Symfony\Component\Lock\Key;
+use Symfony\Component\Lock\LockFactory;
+use Webgriffe\PayumLockRequestExtension\LockRequestExtension;
+use PHPUnit\Framework\TestCase;
+
+class LockRequestExtensionTest extends TestCase
+{
+    private LockRequestExtension $extension;
+
+    private InMemoryStore $lockStore;
+
+    protected function setUp(): void
+    {
+        $this->lockStore = new InMemoryStore();
+        $this->extension = new LockRequestExtension(
+            new LockFactory($this->lockStore),
+        );
+    }
+
+    public function test_it_locks_requests(): void
+    {
+        $context = $this->createContext();
+        $this->extension->onPreExecute($context);
+
+        self::assertTrue($this->lockStore->exists(new Key('webgriffe_payum_lock_request_extension_PaymentClass#5')));
+
+        $this->extension->onPostExecute($context);
+
+        self::assertFalse($this->lockStore->exists(new Key('webgriffe_payum_lock_request_extension_PaymentClass#5')));
+    }
+
+    private function createContext(): Context
+    {
+        $paymentToken = new Token();
+        $paymentToken->setDetails(new Identity(5, 'PaymentClass'));
+        return new Context(
+            new Gateway(),
+            new Capture($paymentToken),
+            [],
+        );
+    }
+}