--- /dev/null
+<?php
+
+/**
+ * @file
+ * Test to ensure theme compatibility with managed files.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\file\Entity\File;
+
+/**
+ * Implements hook_form_system_theme_settings_alter().
+ */
+function test_theme_theme_form_system_theme_settings_alter(&$form, FormStateInterface $form_state) {
+
+ $form['custom_logo'] = [
+ '#type' => 'managed_file',
+ '#title' => t('Secondary logo.'),
+ '#default_value' => theme_get_setting('custom_logo'),
+ '#progress_indicator' => 'bar',
+ '#progress_message' => t('Please wait...'),
+ '#upload_location' => 'public://test',
+ '#upload_validators' => [
+ 'file_validate_extensions' => ['gif png jpg jpeg'],
+ ],
+ ];
+
+ $form['#submit'][] = 'test_theme_theme_form_system_theme_settings_submit';
+}
+
+/**
+ * Test theme form settings submission handler.
+ */
+function test_theme_theme_form_system_theme_settings_submit(&$form, FormStateInterface $form_state) {
+ if ($file_id = $form_state->getValue(['custom_logo', '0'])) {
+ $file = File::load($file_id);
+ $file->setPermanent();
+ $file->save();
+ }
+}