diff --git a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
index 2ae7a736a5cd48b085c60e2adfe39c95b0fadc9d..d61e5016bf5fba64b42af2081e75aeaf51b848b5 100644
--- a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
+++ b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
@@ -683,38 +683,38 @@ public static function providerTestDateDiff() {
         'expected' => $positive_18_hours,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600, new \DateTimeZone('America/Los_Angeles')),
-        'input2' => DateTimePlus::createFromFormat('U', 0, new \DateTimeZone('UTC')),
+        'input1' => DateTimePlus::createFromFormat('U', '3600', new \DateTimeZone('America/Los_Angeles')),
+        'input2' => DateTimePlus::createFromTimestamp(0, new \DateTimeZone('UTC')),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
-        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
+        'input2' => DateTimePlus::createFromTimestamp(0),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
         'input2' => \DateTime::createFromFormat('U', '0'),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
-        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
+        'input2' => DateTimePlus::createFromTimestamp(0),
         'absolute' => TRUE,
         'expected' => $positive_1_hour,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
         'input2' => \DateTime::createFromFormat('U', '0'),
         'absolute' => TRUE,
         'expected' => $positive_1_hour,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 0),
-        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'input1' => DateTimePlus::createFromTimestamp(0),
+        'input2' => DateTimePlus::createFromTimestamp(0),
         'absolute' => FALSE,
         'expected' => $empty_interval,
       ],
@@ -733,12 +733,12 @@ public static function providerTestDateDiff() {
   public static function providerTestInvalidDateDiff() {
     return [
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
         'input2' => '1970-01-01 00:00:00',
         'absolute' => FALSE,
       ],
       [
-        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input1' => DateTimePlus::createFromTimestamp(3600),
         'input2' => NULL,
         'absolute' => FALSE,
       ],
diff --git a/core/tests/Drupal/Tests/Core/Datetime/DrupalDateTimeTest.php b/core/tests/Drupal/Tests/Core/Datetime/DrupalDateTimeTest.php
index 150c3b2d4ed19518a2c5ec0c6bdce5bb5195f3f3..e2938730208ab364f9ca44d4194906bcc34b3716 100644
--- a/core/tests/Drupal/Tests/Core/Datetime/DrupalDateTimeTest.php
+++ b/core/tests/Drupal/Tests/Core/Datetime/DrupalDateTimeTest.php
@@ -98,38 +98,38 @@ public static function providerTestDateDiff() {
         'expected' => $positive_18_hours,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, new \DateTimeZone('America/Los_Angeles'), $settings),
-        'input2' => DrupalDateTime::createFromFormat('U', 0, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromFormat('U', '3600', new \DateTimeZone('America/Los_Angeles'), $settings),
+        'input2' => DrupalDateTime::createFromTimestamp(0, $utc_tz, $settings),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
-        'input2' => DrupalDateTime::createFromFormat('U', 0, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
+        'input2' => DrupalDateTime::createFromTimestamp(0, $utc_tz, $settings),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
         'input2' => \DateTime::createFromFormat('U', '0'),
         'absolute' => FALSE,
         'expected' => $negative_1_hour,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
-        'input2' => DrupalDateTime::createFromFormat('U', 0, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
+        'input2' => DrupalDateTime::createFromTimestamp(0, $utc_tz, $settings),
         'absolute' => TRUE,
         'expected' => $positive_1_hour,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
         'input2' => \DateTime::createFromFormat('U', '0'),
         'absolute' => TRUE,
         'expected' => $positive_1_hour,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 0, $utc_tz, $settings),
-        'input2' => DrupalDateTime::createFromFormat('U', 0, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(0, $utc_tz, $settings),
+        'input2' => DrupalDateTime::createFromTimestamp(0, $utc_tz, $settings),
         'absolute' => FALSE,
         'expected' => $empty_interval,
       ],
@@ -150,12 +150,12 @@ public static function providerTestInvalidDateDiff() {
     $utc_tz = new \DateTimeZone('UTC');
     return [
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
         'input2' => '1970-01-01 00:00:00',
         'absolute' => FALSE,
       ],
       [
-        'input1' => DrupalDateTime::createFromFormat('U', 3600, $utc_tz, $settings),
+        'input1' => DrupalDateTime::createFromTimestamp(3600, $utc_tz, $settings),
         'input2' => NULL,
         'absolute' => FALSE,
       ],