[Serializer] DateTimeNormalizer handling of null and empty values (returning null or empty instead of new object)

src/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php

@@ -67,6 +67,10 @@ class DateTimeNormalizer implements NormalizerInterface, DenormalizerInterface
     {
         $dateTimeFormat = isset($context[self::FORMAT_KEY]) ? $context[self::FORMAT_KEY] : null;
 
+        if ('' === $data || null === $data) {
+            throw new UnexpectedValueException('The data is either an empty string or null, you should pass a string that can be parsed with the passed format or a valid DateTime string.');
+        }
+
         if (null !== $dateTimeFormat) {
             $object = \DateTime::class === $class ? \DateTime::createFromFormat($dateTimeFormat, $data) : \DateTimeImmutable::createFromFormat($dateTimeFormat, $data);
 

src/Symfony/Component/Serializer/Tests/Normalizer/DateTimeNormalizerTest.php

@@ -91,6 +91,24 @@ class DateTimeNormalizerTest extends TestCase
         $this->normalizer->denormalize('invalid date', \DateTimeInterface::class);
     }
 
+    /**
+     * @expectedException \Symfony\Component\Serializer\Exception\UnexpectedValueException
+     * @expectedExceptionMessage The data is either an empty string or null, you should pass a string that can be parsed with the passed format or a valid DateTime string.
+     */
+    public function testDenormalizeNullThrowsException()
+    {
+        $this->normalizer->denormalize(null, \DateTimeInterface::class);
+    }
+
+    /**
+     * @expectedException \Symfony\Component\Serializer\Exception\UnexpectedValueException
+     * @expectedExceptionMessage The data is either an empty string or null, you should pass a string that can be parsed with the passed format or a valid DateTime string.
+     */
+    public function testDenormalizeEmptyStringThrowsException()
+    {
+        $this->normalizer->denormalize('', \DateTimeInterface::class);
+    }
+
     /**
      * @expectedException \Symfony\Component\Serializer\Exception\UnexpectedValueException
      */