Output list of differences to JSON file.

tools/determinism/compare_build_artifacts.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Compare the artifacts from two builds."""
 
 import difflib
 import json
 import optparse
@@ skipping 575 matching lines @@
     max_filepath_len = max(len(n) for n in first_deps)
     for d in first_deps:
       first_file = os.path.join(first_dir, d)
       second_file = os.path.join(second_dir, d)
       result = compare_files(first_file, second_file)
       if result:
         print('  %-*s: %s' % (max_filepath_len, d, result))
 
 
 def compare_build_artifacts(first_dir, second_dir, target_platform,
-                            recursive=False):
+                            json_output, recursive=False):
   """Compares the artifacts from two distinct builds."""
   if not os.path.isdir(first_dir):
     print >> sys.stderr, '%s isn\'t a valid directory.' % first_dir
     return 1
   if not os.path.isdir(second_dir):
     print >> sys.stderr, '%s isn\'t a valid directory.' % second_dir
     return 1
 
   epoch_hex = struct.pack('<I', int(time.time())).encode('hex')
   print('Epoch: %s' %
@@ skipping 48 matching lines @@
       print('  %s' % u)
   if unexpected_equals:
     print('Unexpected files with no diffs:\n')
     for u in unexpected_equals:
       print('  %s' % u)
 
   all_diffs = expected_diffs + unexpected_diffs
   diffs_to_investigate = sorted(set(all_diffs).difference(missing_files))
   compare_deps(first_dir, second_dir, diffs_to_investigate)
 
+  if json_output:
+    try:
+      out = {
+          'expected_diffs': expected_diffs,
+          'unexpected_diffs': unexpected_diffs,
+      }
+      with open(json_output) as f:
+        json.dump(out, f)
+    except Exception as e:
+      print('failed to write json output: %s' % e)
+
   return int(bool(unexpected_diffs))
 
 
 def main():
   parser = optparse.OptionParser(usage='%prog [options]')
   parser.add_option(
       '-f', '--first-build-dir', help='The first build directory.')
   parser.add_option(
       '-s', '--second-build-dir', help='The second build directory.')
   parser.add_option('-r', '--recursive', action='store_true', default=False,
                     help='Indicates if the comparison should be recursive.')
+  parser.add_option('--json-output', help='JSON file to output differences')
   target = {
       'darwin': 'mac', 'linux2': 'linux', 'win32': 'win'
   }.get(sys.platform, sys.platform)
   parser.add_option('-t', '--target-platform', help='The target platform.',
                     default=target, choices=('android', 'mac', 'linux', 'win'))
   options, _ = parser.parse_args()
 
   if not options.first_build_dir:
     parser.error('--first-build-dir is required')
   if not options.second_build_dir:
     parser.error('--second-build-dir is required')
   if not options.target_platform:
     parser.error('--target-platform is required')
 
   return compare_build_artifacts(os.path.abspath(options.first_build_dir),
                                  os.path.abspath(options.second_build_dir),
                                  options.target_platform,
+                                 options.json_output,
                                  options.recursive)
 
 
 if __name__ == '__main__':
   sys.exit(main())