git-cl: Add tests for metrics collection.

Bug: 897394
Change-Id: I07959e870fef4e6a6b8e6e7c974397d3306460c1
Reviewed-on: https://chromium-review.googlesource.com/c/1315839
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
diff --git a/metrics_utils.py b/metrics_utils.py
index 883c694..7815e16 100644
--- a/metrics_utils.py
+++ b/metrics_utils.py
@@ -205,7 +205,7 @@
       arg = arg.split('=')[0]
       if arg in KNOWN_SUBCOMMAND_ARGS:
         known_args.append(arg)
-  return known_args
+  return sorted(known_args)
 
 
 def extract_http_metrics(request_uri, method, status, response_time):