.../Unit/Normalizer/TimestampNormalizerTest.php    | 126 +++++++++++++++++++++
 1 file changed, 126 insertions(+)

diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php
new file mode 100644
index 0000000..f6ddcf2
--- /dev/null
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php
@@ -0,0 +1,126 @@
+<?php
+
+namespace Drupal\Tests\serialization\Unit\Normalizer;
+
+use Drupal\Core\TypedData\Plugin\DataType\IntegerData;
+use Drupal\Core\TypedData\Plugin\DataType\Timestamp;
+use Drupal\Core\TypedData\Type\DateTimeInterface;
+use Drupal\serialization\Normalizer\TimestampNormalizer;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\Serializer\Exception\UnexpectedValueException;
+
+/**
+ * Unit test coverage for the "Timestamp" @DataType.
+ *
+ * @group serialization
+ * @coversDefaultClass \Drupal\serialization\Normalizer\TimestampNormalizer
+ * @see \Drupal\Core\TypedData\Plugin\DataType\Timestamp
+ */
+class TimestampNormalizerTest extends UnitTestCase {
+
+  /**
+   * The tested data type's normalizer.
+   *
+   * @var \Drupal\serialization\Normalizer\TimestampNormalizer
+   */
+  protected $normalizer;
+
+  /**
+   * The tested data type.
+   *
+   * @var \Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem
+   */
+  protected $data;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $this->normalizer = new TimestampNormalizer();
+    $this->data = $this->prophesize(Timestamp::class);
+  }
+
+  /**
+   * @covers ::supportsNormalization
+   */
+  public function testSupportsNormalization() {
+    $this->assertTrue($this->normalizer->supportsNormalization($this->data->reveal()));
+
+    $integer = $this->prophesize(IntegerData::class);
+    $this->assertFalse($this->normalizer->supportsNormalization($integer->reveal()));
+
+    $datetime = $this->prophesize(DateTimeInterface::class);
+    $this->assertFalse($this->normalizer->supportsNormalization($datetime->reveal()));
+  }
+
+  /**
+   * @covers ::supportsDenormalization
+   */
+  public function testSupportsDenormalization() {
+    $this->assertTrue($this->normalizer->supportsDenormalization($this->data->reveal(), Timestamp::class));
+  }
+
+  /**
+   * @covers ::normalize
+   */
+  public function testNormalize() {
+    $expected = ['value' => '2016-11-06T09:02:00+00:00', 'format' => \DateTime::RFC3339];
+
+    $this->data->getValue()
+      ->willReturn(1478422920);
+
+    $normalized = $this->normalizer->normalize($this->data->reveal());
+    $this->assertSame($expected, $normalized);
+  }
+
+  /**
+   * Tests the denormalize function with good data.
+   *
+   * @covers ::denormalize
+   * @dataProvider providerTestDenormalizeValidFormats
+   */
+  public function testDenormalizeValidFormats($value, $expected) {
+    $normalized = ['value' => $value];
+
+    $denormalized = $this->normalizer->denormalize($normalized, Timestamp::class, NULL, []);
+    $this->assertSame(['value' => $expected], $denormalized);
+  }
+
+  /**
+   * Data provider for testDenormalizeValidFormats.
+   *
+   * @return array
+   */
+  public function providerTestDenormalizeValidFormats() {
+    $expected_stamp = 1478422920;
+
+    $data = [];
+
+    $data['U'] = [$expected_stamp, $expected_stamp];
+    $data['RFC3339'] = ['2016-11-06T09:02:00+00:00', $expected_stamp];
+    $data['RFC3339 +0100'] = ['2016-11-06T09:02:00+01:00', $expected_stamp - 1 * 3600];
+    $data['RFC3339 -0600'] = ['2016-11-06T09:02:00-06:00', $expected_stamp + 6 * 3600];
+
+    $data['ISO8601'] = ['2016-11-06T09:02:00+0000', $expected_stamp];
+    $data['ISO8601 +0100'] = ['2016-11-06T09:02:00+0100', $expected_stamp - 1 * 3600];
+    $data['ISO8601 -0600'] = ['2016-11-06T09:02:00-0600', $expected_stamp + 6 * 3600];
+
+    return $data;
+  }
+
+  /**
+   * Tests the denormalize function with bad data.
+   *
+   * @covers ::denormalize
+   */
+  public function testDenormalizeException() {
+    $this->setExpectedException(UnexpectedValueException::class, 'The specified date "2016/11/06 09:02am GMT" is not in an accepted format: "U" (UNIX timestamp), "Y-m-d\TH:i:sO" (ISO 8601), "Y-m-d\TH:i:sP" (RFC 3339).');
+
+    $normalized = ['value' => '2016/11/06 09:02am GMT'];
+
+    $this->normalizer->denormalize($normalized, Timestamp::class, NULL, []);
+  }
+
+}