only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/file/tests/modules/file_test_states/file_test_states.info.yml
@@ -0,0 +1,8 @@
+name: 'File test states'
+type: module
+description: 'Provides a simple form with file fields using states.'
+package: Testing
+version: VERSION
+core: 8.x
+dependencies:
+  - file
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/file/tests/modules/file_test_states/file_test_states.routing.yml
@@ -0,0 +1,7 @@
+example.form:
+  path: '/file-test-states-form'
+  defaults:
+    _title: 'File test states form'
+    _form: '\Drupal\file_test_states\Form\FileTestStatesForm'
+  requirements:
+    _access: 'TRUE'
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/file/tests/modules/file_test_states/src/Form/FileTestStatesForm.php
@@ -0,0 +1,55 @@
+<?php
+
+namespace Drupal\file_test_states\Form;
+
+use Drupal\Core\Form\FormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * A simple form with a file and manage_file to test states.
+ */
+class FileTestStatesForm extends FormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'file_test_states_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $form['toggle'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Toggle fields'),
+    ];
+    $form['managed_file_initially_visible'] = [
+      '#type' => 'managed_file',
+      '#title' => t('Managed File Initially Visible'),
+      '#states' => [
+        'visible'  => [':input[name="toggle"]' => ['checked' => FALSE]],
+      ],
+    ];
+    $form['managed_file_initially_hidden'] = [
+      '#type' => 'managed_file',
+      '#title' => t('Managed File Initially Hidden'),
+      '#states' => [
+        'visible'  => [':input[name="toggle"]' => ['checked' => TRUE]],
+      ],
+    ];
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {}
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/file/tests/src/FunctionalJavascript/FileManagedStateTest.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Drupal\Tests\file\FunctionalJavascript;
+
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+
+/**
+ * Tests access to managed files.
+ *
+ * @group file
+ */
+class FileManagedStateTest extends JavascriptTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['file_test_states', 'file'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+  }
+
+  /**
+   * Tests if public file is always accessible.
+   */
+  public function testFileStateVisible() {
+    $this->drupalLogin($this->drupalCreateUser());
+    $this->drupalGet('file-test-states-form');
+
+    // Wait until the page has fully loaded including the ajax load of the
+    // managed files.
+    $this->assertSession()->assertWaitOnAjaxRequest();
+    $page = $this->getSession()->getPage();
+
+    // Now get the fields from the page.
+    $field_initially_visible = $page->findField('files[managed_file_initially_visible]');
+    $field_initially_hidden = $page->findField('files[managed_file_initially_hidden]');
+
+    // Check that the initially visible managed file is visible.
+    $this->assertTrue($field_initially_visible->isVisible());
+
+    // Check that the initially hidden managed file is hidden.
+    $this->assertFalse($field_initially_hidden->isVisible());
+
+    // Toggle the fields.
+    $page->findField('toggle')->click();
+
+    // Check that the initially visible managed file is now hidden.
+    $this->assertFalse($field_initially_visible->isVisible());
+
+    // Check that the initially hidden managed file is now visible.
+    $this->assertTrue($field_initially_hidden->isVisible());
+  }
+
+}