Fix typo

tests/TripalJobsTest.test

@@ -11,7 +11,7 @@ class TripalJobsTest extends TestCase {
    */
   public function should_create_a_tripal_job() {
     $job_id = tripal_add_job('Test adding jobs', 'tripal', 'tripal_tripal_cron_notification', [], 1);
-    $this->assertTrue(is_numeric($this->job_id));
+    $this->assertTrue(is_numeric($job_id));
 
     // Clean up
     if($job_id) {