Make sure there's a newline for the cron jobs

test/test_batch.py

@@ -1,7 +1,7 @@
 from unittest import TestCase
 from datetime import datetime
 
-from metrik.batch import flows
+from metrik.batch import flows, build_cron_file
 
 
 class BatchTest(TestCase):
@@ -11,3 +11,8 @@ class BatchTest(TestCase):
         for flow_name, flow_class in flows.items():
             assert flow_class(present=present,
                               live=live).get_schedule() is not None
+
+    def test_cron_string(self):
+        cron_string = build_cron_file()
+        assert len(cron_string.split('\n')) == len(flows) + 1
+        assert cron_string[-1] == '\n'