Handle no downloader work gracefully.

workers/data_refinery_workers/downloaders/test_utils.py

@@ -0,0 +1,15 @@
+import os
+
+from django.test import TestCase, tag
+from typing import List
+from unittest.mock import patch, call
+from urllib.error import URLError
+
+from data_refinery_workers.downloaders import utils
+
+class UtilsTestCase(TestCase):
+    def test_no_jobs_to_create(self):
+        """Make sure this function doesn't raise an exception with no files."""
+        create_processor_job_for_original_files([])
+
+        self.assertTrue(True)

workers/data_refinery_workers/downloaders/utils.py

@@ -196,6 +196,10 @@ def create_processor_job_for_original_files(original_files: List[OriginalFile],
 
     """
 
+    # If there's no original files then we've created all the jobs we need to!
+    if len(original_files) == 0:
+        return
+
     # For anything that has raw data there should only be one Sample per OriginalFile
     sample_object = original_files[0].samples.first()
     pipeline_to_apply = determine_processor_pipeline(sample_object, original_files[0])