Fix datetime serialisation (#16)

Signed-off-by: Graham Campbell <[email protected]>

Author: GrahamCampbell

src/CloudEvents/Serializers/ArraySerializer.php

@@ -6,11 +6,15 @@
 use CloudEvents\Serializers\Exceptions\UnsupportedEventSpecVersionException;
 use CloudEvents\V1\CloudEventInterface as V1CloudEventInterface;
 use DateTimeInterface;
+use DateTimeZone;
 
 use function array_merge;
 
 class ArraySerializer
 {
+    private const DATETIME_FORMAT = 'Y-m-d\TH:i:s\Z';
+    private const DATETIME_ZONE = 'UTC';
+
     /**
      * @throws UnsupportedEventSpecVersionException
      * @throws \JsonException
@@ -46,7 +50,9 @@ protected function createPayload(CloudEventInterface $cloudEvent): array
 
     private function formatTime(?DateTimeInterface $time): ?string
     {
-        return $time === null ? null : $time->format(DATE_RFC3339);
+        return $time === null
+            ? null
+            : $time->setTimezone(new DateTimeZone(self::DATETIME_ZONE))->format(self::DATETIME_FORMAT);
     }
 
     /**

tests/CloudEvents/Serializers/ArraySerializerTest.php

@@ -39,7 +39,7 @@ public function testSerialize(): void
                 'datacontenttype' => 'application/json',
                 'dataschema' => 'com.example/schema',
                 'subject' => 'larger-context',
-                'time' => '2018-04-05T17:31:00+00:00',
+                'time' => '2018-04-05T17:31:00Z',
                 'data' => [
                     'key' => 'value',
                 ]

tests/CloudEvents/Serializers/JsonSerializerTest.php

@@ -40,7 +40,7 @@ public function testSerialize(): void
                     'datacontenttype' => 'application/json',
                     'dataschema' => 'com.example/schema',
                     'subject' => 'larger-context',
-                    'time' => '2018-04-05T17:31:00+00:00',
+                    'time' => '2018-04-05T17:31:00Z',
                     'data' => [
                         'key' => 'value',
                     ]