Add --repeat-until-unexpected option to wptrunner

tests/wpt/harness/wptrunner/wptcommandline.py

@@ -72,6 +72,8 @@ def create_parser(product_choices=None):
                         help="Multiplier relative to standard test timeout to use")
     parser.add_argument("--repeat", action="store", type=int, default=1,
                         help="Number of times to run the tests")
+    parser.add_argument("--repeat-until-unexpected", action="store_true", default=None,
+                        help="Run tests in a loop until one returns an unexpected result")
 
     parser.add_argument("--no-capture-stdio", action="store_true", default=False,
                         help="Don't capture stdio and write to logging")

tests/wpt/harness/wptrunner/wptrunner.py

@@ -160,10 +160,15 @@ def run_tests(config, test_paths, product, **kwargs):
             browser_kwargs = get_browser_kwargs(ssl_env=ssl_env, **kwargs)
 
             repeat = kwargs["repeat"]
-            for repeat_count in xrange(repeat):
-                if repeat > 1:
-                    logger.info("Repetition %i / %i" % (repeat_count + 1, repeat))
+            repeat_count = 0
+            repeat_until_unexpected = kwargs["repeat_until_unexpected"]
 
+            while repeat_count < repeat or repeat_until_unexpected:
+                repeat_count += 1
+                if repeat_until_unexpected:
+                    logger.info("Repetition %i" % (repeat_count))
+                elif repeat > 1:
+                    logger.info("Repetition %i / %i" % (repeat_count, repeat))
 
                 unexpected_count = 0
                 logger.suite_start(test_loader.test_ids, run_info)
@@ -208,6 +213,8 @@ def run_tests(config, test_paths, product, **kwargs):
 
                 unexpected_total += unexpected_count
                 logger.info("Got %i unexpected results" % unexpected_count)
+                if repeat_until_unexpected and unexpected_total > 0:
+                    break
                 logger.suite_end()
 
     return unexpected_total == 0