diff --git a/testing/preprocessor_test.py b/testing/preprocessor_test.py
index af9a95aea9b4280fd9ab039ddb76576fa04cb383..c0916efd49f774fb5af32be79ae402a045c59bc6 100644
--- a/testing/preprocessor_test.py
+++ b/testing/preprocessor_test.py
@@ -43,7 +43,8 @@ def list_tifs(products):
     return preprocessed_list
 
 def test_preprocessor(list_tifs):
-    
+    # check if there are preprocessed results in the buckets 
+    assert len(list_tifs) > 0
     for item in list_tifs:
         set_gdal_swift_auth()
         image = gdal.Open('/vsiswift/preprocessor_results/%s' % item, gdal.GA_ReadOnly)