Fix formatting UTC date time

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+-   Fix formatting date time property with UTC time zone [#482](https://github.com/markuspoerschke/iCal/pull/482)
+
 ## [2.9.0] - 2022-12-23
 
 ### Changed

src/Presentation/Component/Property/Value/DateTimeValue.php

@@ -41,6 +41,10 @@ private function convertTimestampToString(Timestamp $timestamp): string
 
     private function convertDateTimeToString(DateTime $dateTime): string
     {
+        if ($dateTime->hasDateTimeZone() && $dateTime->getDateTimeZone()->getName() === 'UTC') {
+            return $dateTime->getDateTime()->format(self::FORMAT_UTC);
+        }
+
         return $dateTime->getDateTime()->format(self::FORMAT);
     }
 

src/Presentation/Factory/DateTimeFactory.php

@@ -37,7 +37,11 @@ public function createProperty(string $propertyName, PointInTime $pointInTime):
      */
     private function getParameters(PointInTime $pointInTime): array
     {
-        if ($pointInTime instanceof DateTime && $pointInTime->hasDateTimeZone()) {
+        if (
+            $pointInTime instanceof DateTime
+            && $pointInTime->hasDateTimeZone()
+            && $pointInTime->getDateTimeZone()->getName() !== 'UTC'
+        ) {
             return [
                 new Property\Parameter('TZID', new TextValue($pointInTime->getDateTimeZone()->getName())),
             ];

tests/Unit/Presentation/Factory/DateTimeFactoryTest.php

@@ -27,4 +27,13 @@ public function testCreateProperty(): void
 
         self::assertSame('DTSTART;TZID=Europe/Berlin:20210122T111213', $property->__toString());
     }
+
+    public function testUtcTimeZone(): void
+    {
+        $dateTime = new DateTime(new PhpDateTimeImmutable('2022-12-25 23:29:00', new DateTimeZone('UTC')), true);
+
+        $property = (new DateTimeFactory())->createProperty('DTSTART', $dateTime);
+
+        self::assertSame('DTSTART:20221225T232900Z', $property->__toString());
+    }
 }