diff --git a/core/modules/language/tests/src/Unit/ConfigurableLanguageUnitTest.php b/core/modules/language/tests/src/Unit/ConfigurableLanguageUnitTest.php
index f3d8d38..74426aa 100644
--- a/core/modules/language/tests/src/Unit/ConfigurableLanguageUnitTest.php
+++ b/core/modules/language/tests/src/Unit/ConfigurableLanguageUnitTest.php
@@ -6,6 +6,7 @@
 
 namespace Drupal\Tests\language\Unit;
 
+use Drupal\Core\Language\Language;
 use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\UnitTestCase;
 
@@ -77,4 +78,107 @@ public function testNegotiationMethodId(){
     $this->assertEquals($this->configurableLanguage->getNegotiationMethodId(), $set_method_id, 'Negotiation Method Identifier written and read correctly.');
   }
 
+  /**
+   * Tests sorting an array of language objects.
+   *
+   * @covers ::sort()
+   *
+   * @dataProvider providerTestSortArrayOfLanguages
+   *
+   * @param \Drupal\Core\Language\LanguageInterface[] $languages
+   *   An array of language objects: a mix of \Drupal\Core\Language\Language and
+   *   \Drupal\language\Entity\ConfigurableLanguage.
+   * @param array $expected
+   *   The expected array of keys.
+   */
+  public function testSortArrayOfLanguages(array $languages, array $expected) {
+    Language::sort($languages);
+    $this->assertSame($expected, array_keys($languages));
+  }
+
+  /**
+   * Provides data for testSortArrayOfLanguages.
+   *
+   * @return array
+   *   An array of test data.
+   */
+  public function providerTestSortArrayOfLanguages() {
+    $language9A = new Language(array('id' => 'dd'));
+    $language9A->setName('A');
+    $language9A->setWeight(9);
+
+    $language10A = new Language(array('id' => 'ee'));
+    $language10A->setName('A');
+    $language10A->setWeight(10);
+
+    $language10B = new Language(array('id' => 'ff'));
+    $language10B->setName('B');
+    $language10B->setWeight(10);
+
+    $language8A = new ConfigurableLanguage(array('id' => 'hh'), 'configurable_language');
+    $language8A->setName('A');
+    $language8A->setWeight(8);
+
+    $language10C = new ConfigurableLanguage(array('id' => 'hh'), 'configurable_language');
+    $language10C->setName('C');
+    $language10C->setWeight(10);
+
+    return array(
+      // Set up data set #0, already ordered by weight.
+      array(
+        // Set the data.
+        array(
+          $language8A->getId() => $language8A,
+          $language9A->getId() => $language9A,
+          $language10B->getId() => $language10B,
+        ),
+        // Set the expected key order.
+        array(
+          $language8A->getId(),
+          $language9A->getId(),
+          $language10B->getId(),
+        ),
+      ),
+      // Set up data set #1, out of order by weight.
+      array(
+        array(
+          $language10B->getId() => $language10B,
+          $language10C->getId() => $language8A,
+          $language9A->getId() => $language9A,
+        ),
+        array(
+          $language8A->getId(),
+          $language9A->getId(),
+          $language10B->getId(),
+        ),
+      ),
+      // Set up data set #2, tied by weight, already ordered by name.
+      array(
+        array(
+          $language10A->getId() => $language10A,
+          $language10B->getId() => $language10B,
+          $language10C->getId() => $language10C,
+        ),
+        array(
+          $language10A->getId(),
+          $language10B->getId(),
+          $language10C->getId(),
+        ),
+      ),
+      // Set up data set #3, tied by weight, out of order by name.
+      array(
+        array(
+          $language10B->getId() => $language10B,
+          $language10C->getId() => $language10C,
+          $language10A->getId() => $language10A,
+        ),
+        array(
+          $language10A->getId(),
+          $language10B->getId(),
+          $language10C->getId(),
+        ),
+      ),
+    );
+  }
+
 }