Improve tool that analyzes gm JSON summary

gm/confirm_no_failures_in_json.py

-#!/usr/bin/env python
-# Copyright (c) 2013 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.
-
-"""Utility to confirm that a JSON summary written by GM contains no failures.
-
-Usage:
-  python confirm_no_failures_in_json.py <filename>
-"""
-
-__author__ = 'Elliot Poger'
-
-
-import json
-import sys
-
-
-# These constants must be kept in sync with the kJsonKey_ constants in
-# gm_expectations.cpp !
-JSONKEY_ACTUALRESULTS = 'actual-results'
-JSONKEY_ACTUALRESULTS_FAILED = 'failed'
-
-# This is the same indent level as used by jsoncpp, just for consistency.
-JSON_INDENTLEVEL = 3
-
-
-def Assert(filepath):
-  """Raises an exception if the JSON summary at filepath contains any failed
-  tests, or if we were unable to read the JSON summary."""
-  failed_tests = GetFailedTests(filepath)
-  if failed_tests:
-    raise Exception('JSON file %s contained these test failures...\n%s' % (
-        filepath, json.dumps(failed_tests, indent=JSON_INDENTLEVEL)))
-
-
-def GetFailedTests(filepath):
-  """Returns the dictionary of failed tests from the JSON file at filepath."""
-  json_dict = json.load(open(filepath))
-  actual_results = json_dict[JSONKEY_ACTUALRESULTS]
-  return actual_results[JSONKEY_ACTUALRESULTS_FAILED]
-
-
-if '__main__' == __name__:
-  if len(sys.argv) != 2:
-    raise Exception('usage: %s <input-json-filepath>' % sys.argv[0])
-  Assert(sys.argv[1])