diff --git a/core/modules/migrate/tests/src/Unit/process/FormatDateTest.php b/core/modules/migrate/tests/src/Unit/process/FormatDateTest.php
index 970aa65..d778595 100644
--- a/core/modules/migrate/tests/src/Unit/process/FormatDateTest.php
+++ b/core/modules/migrate/tests/src/Unit/process/FormatDateTest.php
@@ -15,11 +15,14 @@
 class FormatDateTest extends MigrateProcessTestCase {
 
   /**
-   * {@inheritdoc}
+   * Tests the assumption that local time is in 'Australia/Sydney'.
    */
-  public function setUp() {
-    parent::setUp();
-    date_default_timezone_set('UTC');
+  public function testLocalTimeZone() {
+    // @todo The 'Australia/Sydney' time zone is set in core/tests/bootstrap.php
+    // This assertion checks that the assumptions about local time in the rest
+    // of the test methods are accurate. This should be removed when
+    // @link https://www.drupal.org/node/2889803 @endlink is committed.
+    $this->assertEquals('Australia/Sydney', date_default_timezone_get());
   }
 
   /**
@@ -74,14 +77,14 @@ public function testMigrateExceptionBadFormat() {
    */
   public function testDeprecatedTimezoneConfigurationKey() {
     $configuration = [
-      'from_format' => 'Y-m-d\TH:i:sO',
-      'to_format' => 'Y-m-d\TH:i:s',
+      'from_format' => 'Y-m-d\TH:i:s',
+      'to_format' => 'Y-m-d\TH:i:s e',
       'timezone' => 'America/Managua',
     ];
     $this->plugin = new FormatDate($configuration, 'test_format_date', []);
-    $actual = $this->plugin->transform('2004-12-19T10:19:42-0600', $this->migrateExecutable, $this->row, 'field_date');
+    $actual = $this->plugin->transform('2004-12-19T10:19:42', $this->migrateExecutable, $this->row, 'field_date');
 
-    $this->assertEquals('2004-12-19T10:19:42', $actual);
+    $this->assertEquals('2004-12-19T10:19:42 America/Managua', $actual);
   }
 
   /**