.../Normalizer/DateTimeIso8601NormalizerTest.php   | 48 +++++++++++++++++-----
 1 file changed, 38 insertions(+), 10 deletions(-)

diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
index b3cf2ae..ffd3f23 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
@@ -11,6 +11,7 @@
 use Drupal\Core\TypedData\Plugin\DataType\IntegerData;
 use Drupal\Core\TypedData\Type\DateTimeInterface;
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
 use Drupal\serialization\Normalizer\DateTimeIso8601Normalizer;
 use Drupal\Tests\UnitTestCase;
 use Prophecy\Argument;
@@ -187,12 +188,13 @@ public function providerTestNormalize() {
    * @covers ::denormalize
    * @dataProvider providerTestDenormalizeValidFormats
    */
-  public function testDenormalizeValidFormats($normalized, $expected) {
-    $denormalized = $this->normalizer->denormalize($normalized, DateTimeIso8601::class, NULL, []);
-    $this->assertInstanceOf(\DateTime::class, $denormalized);
-    $this->assertEquals('UTC', $denormalized->getTimezone()->getName());
-    $this->assertEquals('12:00:00', $denormalized->format('H:i:s'));
-    $this->assertEquals($expected->format(\DateTime::RFC3339), $denormalized->format(\DateTime::RFC3339));
+  public function testDenormalizeValidFormats($type, $normalized, $expected) {
+    $field_definition = $this->prophesize(FieldDefinitionInterface::class);
+    $field_definition->getSetting('datetime_type')->willReturn($type === 'date-only' ? DateTimeItem::DATETIME_TYPE_DATE : DateTimeItem::DATETIME_TYPE_DATETIME);
+    $denormalized = $this->normalizer->denormalize($normalized, DateTimeIso8601::class, NULL, [
+      'field_definition' => $field_definition->reveal(),
+    ]);
+    $this->assertSame($expected, $denormalized);
   }
 
   /**
@@ -202,21 +204,47 @@ public function testDenormalizeValidFormats($normalized, $expected) {
    */
   public function providerTestDenormalizeValidFormats() {
     $data = [];
-    $data['denormalized dates have the UTC timezone'] = ['2016-11-06', new \DateTimeImmutable('2016-11-06T12:00:00', new \DateTimeZone('UTC'))];
+    $data['just a date'] = ['date-only', '2016-11-06', '2016-11-06'];
+
+    $data['RFC3339'] = ['date+time', '2016-11-06T09:02:00+00:00', '2016-11-06T09:02:00'];
+    $data['RFC3339 +0100'] = ['date+time', '2016-11-06T09:02:00+01:00', '2016-11-06T08:02:00'];
+    $data['RFC3339 -0600'] = ['date+time', '2016-11-06T09:02:00-06:00', '2016-11-06T15:02:00'];
+
+    $data['ISO8601'] = ['date+time', '2016-11-06T09:02:00+0000', '2016-11-06T09:02:00'];
+    $data['ISO8601 +0100'] = ['date+time', '2016-11-06T09:02:00+0100', '2016-11-06T08:02:00'];
+    $data['ISO8601 -0600'] = ['date+time', '2016-11-06T09:02:00-0600', '2016-11-06T15:02:00'];
+
     return $data;
   }
 
   /**
-   * Tests the denormalize function with bad data.
+   * Tests the denormalize function with bad data for the date-only case.
    *
    * @covers ::denormalize
    */
-  public function testDenormalizeException() {
+  public function testDenormalizeDateOnlyException() {
     $this->setExpectedException(UnexpectedValueException::class, 'The specified date "2016/11/06" is not in an accepted format: "Y-m-d" (date-only).');
 
     $normalized = '2016/11/06';
 
-    $this->normalizer->denormalize($normalized, DateTimeIso8601::class, NULL, []);
+    $field_definition = $this->prophesize(FieldDefinitionInterface::class);
+    $field_definition->getSetting('datetime_type')->willReturn(DateTimeItem::DATETIME_TYPE_DATE);
+    $this->normalizer->denormalize($normalized, DateTimeIso8601::class, NULL, ['field_definition' => $field_definition->reveal()]);
+  }
+
+  /**
+   * Tests the denormalize function with bad data for the date+time case.
+   *
+   * @covers ::denormalize
+   */
+  public function testDenormalizeDateAndTimeException() {
+    $this->setExpectedException(UnexpectedValueException::class, 'The specified date "2016-11-06T08:00:00" is not in an accepted format: "Y-m-d\TH:i:sP" (RFC 3339), "Y-m-d\TH:i:sO" (ISO 8601).');
+
+    $normalized = '2016-11-06T08:00:00';
+
+    $field_definition = $this->prophesize(FieldDefinitionInterface::class);
+    $field_definition->getSetting('datetime_type')->willReturn(DateTimeItem::DATETIME_TYPE_DATETIME);
+    $this->normalizer->denormalize($normalized, DateTimeIso8601::class, NULL, ['field_definition' => $field_definition->reveal()]);
   }
 
 }