Add unit test to hit class-loader issue

tests/phpunit/CRM/Contribute/Import/Parser/ContributionTest.php

@@ -9,6 +9,7 @@
 use Civi\Api4\DedupeRule;
 use Civi\Api4\DedupeRuleGroup;
 use Civi\Api4\Email;
+use Civi\Api4\Import;
 use Civi\Api4\Note;
 use Civi\Api4\OptionValue;
 use Civi\Api4\UserJob;
@@ -817,4 +818,14 @@ protected function addToDedupeRule(): void {
     ]);
   }
 
+  /**
+   * Test the Import api works from the extension when the extension is enabled after the import.
+   */
+  public function testEnableExtension(): void {
+    $this->importContributionsDotCSV();
+    $this->callAPISuccess('Extension', 'enable', ['key' => 'civiimport']);
+    $result = Import::get($this->userJobID)->execute();
+    $this->assertEquals('Valid', $result->first()['_status']);
+  }
+
 }