Add a unit test for run_test_cases.py.

tools/isolate/run_test_cases.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Runs each test cases as a single shard, single process execution.
 
 Similar to sharding_supervisor.py but finer grained. Runs multiple instances in
 parallel.
 """
@@ skipping 99 matching lines @@
     ]
   if whitelist:
     tests = [
       t for t in tests if any(fnmatch.fnmatch(t, s) for s in whitelist)
     ]
   logging.info(
       'Found %d test cases in %s' % (len(tests), os.path.basename(executable)))
   return tests
 
 
-def run_test_cases(executable, whitelist, blacklist, jobs, timeout, stats_only):
+def run_test_cases(
+    executable, whitelist, blacklist, jobs, timeout, stats_only, no_dump):
   """Traces test cases one by one."""
   test_cases = get_test_cases(executable, whitelist, blacklist)
   if not test_cases:
     return
 
   progress = worker_pool.Progress(len(test_cases))
   with worker_pool.ThreadPool(jobs or multiprocessing.cpu_count()) as pool:
     function = Runner(executable, os.getcwd(), timeout, progress).map
     for test_case in test_cases:
       pool.add_task(function, test_case)
     results = pool.join(progress, 0.1)
     duration = time.time() - progress.start
   results = dict((item[0]['test_case'], item) for item in results)
-  trace_inputs.write_json('%s.run_test_cases' % executable, results, False)
-  print ''
+  if not no_dump:
+    trace_inputs.write_json('%s.run_test_cases' % executable, results, False)
+  sys.stderr.write('\n')
   total = len(results)
   if not total:
     return 1
 
   # Classify the results
   success = []
   flaky = []
   fail = []
   nb_runs = 0
   for test_case in sorted(results):
@@ skipping 54 matching lines @@
       help='Timeout for a single test case, in seconds default:%default')
   parser.add_option(
       '-s', '--stats',
       action='store_true',
       help='Only prints stats, not output')
   parser.add_option(
       '-v', '--verbose',
       action='count',
       default=int(os.environ.get('ISOLATE_DEBUG', 0)),
       help='Use multiple times')
+  parser.add_option(
+      '--no-dump',
+      action='store_true',
+      help='do not generate a .test_cases file')
   options, args = parser.parse_args()
   levels = [logging.ERROR, logging.WARNING, logging.INFO, logging.DEBUG]
   logging.basicConfig(
       level=levels[min(len(levels)-1, options.verbose)],
       format='%(levelname)5s %(module)15s(%(lineno)3d): %(message)s')
 
   if len(args) != 1:
     parser.error(
         'Please provide the executable line to run, if you need fancy things '
         'like xvfb, start this script from *inside* xvfb, it\'ll be much faster'
         '.')
   return run_test_cases(
       args[0],
       options.whitelist,
       options.blacklist,
       options.jobs,
       options.timeout,
-      options.stats)
+      options.stats,
+      options.no_dump)
 
 
 if __name__ == '__main__':
   sys.exit(main())