Add a tool to query the Rietveld approvers for an issue.

tools/rietveld_approvers_for_issue.py

Index: tools/rietveld_approvers_for_issue.py
diff --git a/tools/rietveld_approvers_for_issue.py b/tools/rietveld_approvers_for_issue.py
new file mode 100755
index 0000000000000000000000000000000000000000..4bff91c9157d2d95fbee8b11e60be03690fec447
--- /dev/null
+++ b/tools/rietveld_approvers_for_issue.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from __future__ import print_function
+
+
+import argparse
+import json
+import os
+import sys
+import urllib2
+
+
+def main(argv):
+  parser = argparse.ArgumentParser()
+  parser.add_argument('issue', action='store', type=int)
+  args = parser.parse_args(argv)
+
+  try:
+    for approver in rietveld_approvers_for_issue(args.issue):
+      print(approver)
+    return 0
+  except Exception as e:
+    print('Exception raised: %s' % str(e), file=sys.stderr)
+    return 1
+
+
+def rietveld_approvers_for_issue(issue):
+  """Returns a sorted list of the approves for a given Rietveld issue."""
+
+  url = 'https://codereview.chromium.org/api/%d?messages=true' % issue
+  fp = None
+  try:
+    fp = urllib2.urlopen(url)
+    issue_props = json.load(fp)
+    messages = issue_props.get('messages', [])
+    return sorted(set(m['sender'] for m in messages if m.get('approval')))
+  finally:
+    if fp:
+      fp.close()
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv[1:]))