diff --git a/core/modules/file/tests/file_module_test.module b/core/modules/file/tests/file_module_test.module
index 490ef42..8904b7b 100644
--- a/core/modules/file/tests/file_module_test.module
+++ b/core/modules/file/tests/file_module_test.module
@@ -29,6 +29,7 @@ function file_module_test_menu() {
  * @ingroup forms
  */
 function file_module_test_form($form, &$form_state, $tree = TRUE, $extended = FALSE, $default_fid = NULL) {
+
   $form['#tree'] = (bool) $tree;
 
   $form['nested']['file'] = array(
@@ -42,12 +43,21 @@ function file_module_test_form($form, &$form_state, $tree = TRUE, $extended = FA
   if ($default_fid) {
     $form['nested']['file']['#default_value'] = $extended ? array('fid' => $default_fid) : $default_fid;
   }
+  if (isset($form_state['clicked_button']) && $form_state['clicked_button']['#value'] == t('Continue submit')) {
+    $form['nested']['file']['#access'] = FALSE;
+  }
 
   $form['textfield'] = array(
     '#type' => 'textfield',
     '#title' => t('Type a value and ensure it stays'),
   );
 
+  $form['continue_submit'] = array(
+    '#type' => 'submit',
+    '#value' => t('Continue submit'),
+    '#submit' => array('file_module_test_form_continue_submit'),
+  );
+
   $form['submit'] = array(
     '#type' => 'submit',
     '#value' => t('Save'),
@@ -57,6 +67,14 @@ function file_module_test_form($form, &$form_state, $tree = TRUE, $extended = FA
 }
 
 /**
+ * Form submit handler to continue multi-step form.
+ */
+function file_module_test_form_continue_submit($form, &$form_state) {
+  drupal_set_message(t('Continue button clicked.'));
+  $form_state['rebuild'] = TRUE;
+}
+
+/**
  * Form submission handler for file_module_test_form().
  */
 function file_module_test_form_submit($form, &$form_state) {