Issue #3456417 by eugene bocharov, pablo_pukha, smustgrave, oily, andypost:...

Issue #3456417 by eugene bocharov, pablo_pukha, smustgrave, oily, andypost: [regression] DateHelper::dayOfWeekName() returns untranslated name

(cherry picked from commit 3aaf8f3b)

core/lib/Drupal/Core/Datetime/DateHelper.php

@@ -521,7 +521,7 @@ public static function dayOfWeek($date = NULL) {
    *   (optional) Whether to return the abbreviated name for that day.
    *   Defaults to TRUE.
    *
-   * @return string|null
+   * @return \Drupal\Core\StringTranslation\TranslatableMarkup|null
    *   The name of the day in the week for that date, or null if the $date has
    *   errors.
    */
@@ -533,7 +533,7 @@ public static function dayOfWeekName($date = NULL, $abbr = TRUE) {
     if (!$date->hasErrors()) {
       $dow = self::dayOfWeek($date);
       $days = $abbr ? self::weekDaysAbbr() : self::weekDays();
-      return $days[$dow]->getUntranslatedString();
+      return $days[$dow];
     }
     return NULL;
   }

core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php

@@ -7,6 +7,7 @@
 use Drupal\Core\Datetime\DateHelper;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Language\Language;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -31,6 +32,7 @@ protected function setUp(): void {
     $container = new ContainerBuilder();
     $config = ['system.date' => ['first_day' => 'Sunday']];
     $container->set('config.factory', $this->getConfigFactoryStub($config));
+    $container->set('string_translation', $this->getStringTranslationStub());
 
     $this->languageManager = $this->createMock('\Drupal\Core\Language\LanguageManagerInterface');
     $language = new Language(['langcode' => 'en']);
@@ -245,6 +247,9 @@ public function testDayOfWeekName(): void {
     $this->assertNotNull(DateHelper::dayOfWeekName(FALSE));
     $this->assertNotNull(DateHelper::dayOfWeekName(''));
 
+    // Ensure proper return value type.
+    $this->assertInstanceOf(TranslatableMarkup::class, DateHelper::dayOfWeekName());
+
     // Pass nothing and expect to get NULL.
     $this->assertNull(DateHelper::dayOfWeekName(0));
     $this->assertNull(DateHelper::dayOfWeekName('0'));