#539022 follow-up by David_Rothstein: Batch API should use the current theme to run the batches.

includes/batch.inc

@@ -16,6 +16,26 @@
  * @see batch_get()
  */
 
+/**
+ * Loads a batch from the database.
+ *
+ * @param $id
+ *   The ID of the batch to load. When a progressive batch is being processed,
+ *   the relevant ID is found in $_REQUEST['id'].
+ * @return
+ *   An array representing the batch, or FALSE if no batch was found.
+ */
+function batch_load($id) {
+  $batch = db_query("SELECT batch FROM {batch} WHERE bid = :bid AND token = :token", array(
+    ':bid' => $id,
+    ':token' => drupal_get_token($id),
+  ))->fetchField();
+  if ($batch) {
+    return unserialize($batch);
+  }
+  return FALSE;
+}
+
 /**
  * State-based dispatcher for the batch processing page.
  *
@@ -28,19 +48,15 @@ function _batch_page() {
     return FALSE;
   }
 
-  // Retrieve the current state of batch from db.
-  $batch = db_query("SELECT batch FROM {batch} WHERE bid = :bid AND token = :token", array(
-    ':bid' => $_REQUEST['id'],
-    ':token' => drupal_get_token($_REQUEST['id']))
-  )->fetchField();
-
+  // Retrieve the current state of the batch.
   if (!$batch) {
-    drupal_set_message(t('No active batch.'), 'error');
-    drupal_goto();
+    $batch = batch_load($_REQUEST['id']);
+    if (!$batch) {
+      drupal_set_message(t('No active batch.'), 'error');
+      drupal_goto();
+    }
   }
 
-  $batch = unserialize($batch);
-
   // Register database update for the end of processing.
   register_shutdown_function('_batch_shutdown');
 

modules/simpletest/tests/batch.test

@@ -6,6 +6,40 @@
  * Unit tests for the Drupal Batch API.
  */
 
+/**
+ * Tests for the batch API progress page theme.
+ */
+class BatchAPIThemeTestCase extends DrupalWebTestCase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Batch API progress page theme',
+      'description' => 'Tests that while a progressive batch is running, it correctly uses the theme of the page that started the batch.',
+      'group' => 'Batch API',
+    );
+  }
+
+  function setUp() {
+    parent::setUp('system_test');
+    // Make sure that the page which starts the batch (an administrative page)
+    // is using a different theme than would normally be used by the batch API.
+    variable_set('theme_default', 'garland');
+    variable_set('admin_theme', 'seven');
+  }
+
+  /**
+   * Tests that the batch API progress page uses the correct theme.
+   */
+  function testBatchAPIProgressPageTheme() {
+    // Visit an administrative page that runs a test batch, and check that the
+    // theme that was used during batch execution (which the batch callback
+    // function saved as a variable) matches the theme used on the
+    // administrative page.
+    $this->drupalGet('admin/system-test/batch-theme');
+    $batch_theme_used = variable_get('system_test_batch_theme_used', 'garland');
+    $this->assertEqual($batch_theme_used, 'seven', t('A progressive batch correctly uses the theme of the page that started the batch.'));
+  }
+}
+
 /**
  * Tests the function _batch_api_percentage() to make sure that the rounding
  * works properly in all cases.

modules/simpletest/tests/system_test.module

@@ -5,6 +5,11 @@
  * Implement hook_menu().
  */
 function system_test_menu() {
+  $items['admin/system-test/batch-theme'] = array(
+    'page callback' => 'system_test_batch_theme',
+    'access callback' => TRUE,
+    'type' => MENU_CALLBACK,
+  );    
   $items['system-test/sleep/%'] = array(
     'page callback' => 'system_test_sleep',
     'page arguments' => array(2),
@@ -97,6 +102,34 @@ function system_test_menu() {
   return $items;
 }
 
+/**
+ * Menu callback; start a new batch for testing the batch progress page theme.
+ */
+function system_test_batch_theme() {
+  $batch = array(
+    'operations' => array(
+      array('system_test_batch_theme_callback', array()),
+    ),
+  );
+  batch_set($batch);
+  // Force the batch to redirect to some page other than this one (to avoid an
+  // infinite loop).
+  batch_process('node');
+}
+
+/**
+ * Batch callback function for testing the theme used by a batch.
+ */
+function system_test_batch_theme_callback() {
+  // Because drupalGet() steps through the full progressive batch before
+  // returning control to the test function, we cannot test that the correct
+  // theme is being used on the batch processing page by viewing that page
+  // directly. Instead, we save the theme being used in a variable here, so
+  // that it can be loaded and inspected in the thread running the test.
+  global $theme;
+  variable_set('system_test_batch_theme_used', $theme);
+}
+
 function system_test_sleep($seconds) {
   sleep($seconds);
 }

modules/system/system.admin.inc

@@ -2054,10 +2054,6 @@ function system_batch_page() {
   require_once DRUPAL_ROOT . '/includes/batch.inc';
   $output = _batch_page();
 
-  // Use the same theme that the page that started the batch.
-  $batch = &batch_get();
-  $GLOBALS['custom_theme'] = $batch['theme'];
-
   if ($output === FALSE) {
     drupal_access_denied();
   }

modules/system/system.module

@@ -993,12 +993,29 @@ function system_menu() {
   $items['batch'] = array(
     'page callback' => 'system_batch_page',
     'access callback' => TRUE,
+    'theme callback' => '_system_batch_theme',
     'type' => MENU_CALLBACK,
     'file' => 'system.admin.inc',
   );
   return $items;
 }
 
+/**
+ * Theme callback for the default batch page.
+ */
+function _system_batch_theme() {
+  // Retrieve the current state of the batch.
+  $batch = &batch_get();
+  if (!$batch && isset($_REQUEST['id'])) {
+    require_once DRUPAL_ROOT . '/includes/batch.inc';
+    $batch = batch_load($_REQUEST['id']);
+  }
+  // Use the same theme as the page that started the batch.
+  if (!empty($batch['theme'])) {
+    return $batch['theme'];
+  }
+}
+
 /**
  * Implementation of hook_library().
  */