Issue #3243422: Add a kernel test of WritableFileSystemValidator

src/Validator/WritableFileSystemValidator.php

@@ -48,27 +48,40 @@ class WritableFileSystemValidator implements EventSubscriberInterface {
   }
 
   /**
-   * Checks that the file system is writable.
+   * Wrapper around is_writable().
    *
-   * @param \Drupal\automatic_updates\Event\UpdateEvent $event
-   *   The event object.
+   * @param string $path
+   *   The path to check.
+   *
+   * @return bool
+   *   TRUE if the given path is writable, otherwise FALSE.
    *
    * @todo It might make sense to use a more sophisticated method of testing
    *   writability than is_writable(), since it's not clear if that can return
    *   false negatives/positives due to things like SELinux, exotic file
    *   systems, and so forth.
    */
+  protected function isWritable(string $path): bool {
+    return is_writable($path);
+  }
+
+  /**
+   * Checks that the file system is writable.
+   *
+   * @param \Drupal\automatic_updates\Event\UpdateEvent $event
+   *   The event object.
+   */
   public function checkPermissions(UpdateEvent $event): void {
     $messages = [];
 
-    if (!is_writable($this->appRoot)) {
+    if (!$this->isWritable($this->appRoot)) {
       $messages[] = $this->t('The Drupal directory "@dir" is not writable.', [
         '@dir' => $this->appRoot,
       ]);
     }
 
     $dir = $this->pathLocator->getVendorDirectory();
-    if (!is_writable($dir)) {
+    if (!$this->isWritable($dir)) {
       $messages[] = $this->t('The vendor directory "@dir" is not writable.', ['@dir' => $dir]);
     }