add failing test for serializing created_at event property

tests/EventSerializers/EventSerializerTest.php

@@ -8,13 +8,15 @@
 
 use function PHPUnit\Framework\assertEquals;
 use function PHPUnit\Framework\assertInstanceOf;
+use function PHPUnit\Framework\assertStringContainsString;
 
 use Spatie\EventSourcing\EventSerializers\EventSerializer;
 use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithArray;
 use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithCarbon;
 use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithDatetime;
 use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithDocblock;
 use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithoutSerializedModels;
+use Spatie\EventSourcing\Tests\TestClasses\Events\EventWithCreatedAtProperty;
 use Spatie\EventSourcing\Tests\TestClasses\Events\MoneyAddedEvent;
 use Spatie\EventSourcing\Tests\TestClasses\EventSerializer\UpgradeSerializer;
 use Spatie\EventSourcing\Tests\TestClasses\Models\Account;
@@ -74,6 +76,18 @@
     assertInstanceOf(DateTimeImmutable::class, $normalizedEvent->value);
 });
 
+it('does not modify `created_at` event properties', function() {
+    $event = new EventWithCreatedAtProperty('2020-01-01 00:00:00');
+
+    $json = $this->eventSerializer->serialize($event);
+
+    assertEquals('{"created_at":"2020-01-01 00:00:00"}', $json);
+
+    $normalizedEvent = $this->eventSerializer->deserialize(get_class($event), $json, 1);
+
+    assertEquals('2020-01-01 00:00:00', $normalizedEvent->created_at);
+});
+
 it('can deserialize an event with carbon', function () {
     $event = new EventWithCarbon(Carbon::now());
 

tests/TestClasses/Events/EventWithCreatedAtProperty.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Spatie\EventSourcing\Tests\TestClasses\Events;
+
+use Spatie\EventSourcing\StoredEvents\ShouldBeStored;
+
+class EventWithCreatedAtProperty extends ShouldBeStored
+{
+    public string $created_at;
+
+    public function __construct(string $created_at)
+    {
+        $this->created_at = $created_at;
+    }
+}