Issue #3002522 by andypost, Matthijs, tim.plunkett, wizonesolutions: Calling...

Issue #3002522 by andypost, Matthijs, tim.plunkett, wizonesolutions: Calling StatusMessages::renderMessages() with a  returns a faulty render array

core/lib/Drupal/Core/Render/Element/StatusMessages.php

@@ -76,7 +76,9 @@ public static function generatePlaceholder(array $element) {
   public static function renderMessages($type = NULL) {
     $render = [];
     if (isset($type)) {
-      $messages = \Drupal::messenger()->deleteByType($type);
+      $messages = [
+        $type => \Drupal::messenger()->deleteByType($type),
+      ];
     }
     else {
       $messages = \Drupal::messenger()->deleteAll();

core/tests/Drupal/KernelTests/Core/Theme/MessageTest.php

@@ -32,6 +32,14 @@ public function testMessages() {
     $this->render($messages);
     $this->assertRaw('messages messages--error');
     $this->assertRaw('messages messages--status');
+    // Tests display of only one type of messages.
+    \Drupal::messenger()->addError('An error occurred');
+    $messages = [
+      '#type' => 'status_messages',
+      '#display' => 'error',
+    ];
+    $this->render($messages);
+    $this->assertRaw('messages messages--error');
   }
 
 }