Issue #3028621 by jungle, John Cook: BatchBuilder included files fails

core/lib/Drupal/Core/Batch/BatchBuilder.php

@@ -205,12 +205,18 @@ public function setErrorMessage($message) {
    * The path should be relative to base_path(), and thus should be built using
    * drupal_get_path(). Defaults to {module_name}.module.
    *
+   * The file needs to be set before using ::addOperation(),
+   * ::setFinishCallback(), or any other function that uses callbacks from the
+   * file. This is so that PHP knows about the included functions.
+   *
    * @param string $filename
    *   The path to the file.
    *
    * @return $this
    */
   public function setFile($filename) {
+    include_once $filename;
+
     $this->file = $filename;
     return $this;
   }

core/tests/Drupal/Tests/Core/Batch/BatchBuilderTest.php

@@ -113,11 +113,20 @@ public function testSetErrorMessage() {
    * @covers ::setFile
    */
   public function testSetFile() {
+    $filename = dirname(__DIR__, 6) . '/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc';
+    $this->assertIsNotCallable('_batch_test_callback_1');
+    $this->assertIsNotCallable('_batch_test_finished_1');
+
     $batch = (new BatchBuilder())
-      ->setFile('filename.php')
+      ->setFile($filename)
+      ->setFinishCallback('_batch_test_finished_1')
+      ->addOperation('_batch_test_callback_1', [])
       ->toArray();
-
-    $this->assertEquals('filename.php', $batch['file']);
+    $this->assertEquals($filename, $batch['file']);
+    $this->assertEquals([['_batch_test_callback_1', []]], $batch['operations']);
+    $this->assertEquals('_batch_test_finished_1', $batch['finished']);
+    $this->assertIsCallable('_batch_test_callback_1');
+    $this->assertIsCallable('_batch_test_finished_1');
   }
 
   /**