Add bisect config validation.

scripts/slave/recipe_modules/auto_bisect/bisector.py

Index: scripts/slave/recipe_modules/auto_bisect/bisector.py
diff --git a/scripts/slave/recipe_modules/auto_bisect/bisector.py b/scripts/slave/recipe_modules/auto_bisect/bisector.py
index e6caa9b47da7853f5ece3715996a20bd77c01c86..83b31642f346e895f03dbe81a775a9d839be1a75 100644
--- a/scripts/slave/recipe_modules/auto_bisect/bisector.py
+++ b/scripts/slave/recipe_modules/auto_bisect/bisector.py
@@ -7,6 +7,7 @@ import re
 import time
 import urllib
 
+from . import config_validation
 from . import depot_config
 from . import revision_state
 
@@ -75,11 +76,11 @@ class Bisector(object):
     """
     super(Bisector, self).__init__()
     self._api = api
+    self.result_codes = set()
     self.ensure_sync_master_branch()
     self.bisect_config = bisect_config
     self.config_step()
     self.revision_class = revision_class
-    self.result_codes = set()
     self.last_tested_revision = None
 
     # Test-only properties.
@@ -189,8 +190,9 @@ class Bisector(object):
     return significantly_different
 
   def config_step(self):
-    """Yields a simple echo step that outputs the bisect config."""
+    """Validates the config and yields a step that prints the bisect config."""
     api = self.api
+
     # bisect_config may come as a FrozenDict (which is not serializable).
     bisect_config = dict(self.bisect_config)
 
@@ -201,12 +203,19 @@ class Bisector(object):
     for k, v in bisect_config.iteritems():
       if isinstance(v, basestring):
         bisect_config[k] = fix_windows_backslashes(v)
+
+    step = api.m.step('config', [])
+    try:
+      config_validation.validate_config(bisect_config)
+    except config_validation.ValidationFail as error:
+      self.surface_result('BAD_CONFIG')
+      raise self.api.m.step.StepFailure(error.message)

[qyearsley, 2016/03/11 01:41:34]

Would this provide everything in the buildbot job UI that we want? Or should I
print the error message in some other way?

[RobertoCN, 2016/03/14 01:26:23]

Just set the step to failed as well before raising the StepFailure:
self.api.m.step.active_result.presentation.status = self.api.m.step.FAILURE

If you wanted the failure to be its own step you could use the halt recipe
module.

[qyearsley, 2016/03/18 22:50:19]

Done; making it it's own step may make it be clearer when it fails.

+
     # We sort the keys to prevent problems with orders changing when
     # recipe_simulation_test compares against expectation files.
     config_string = json.dumps(bisect_config, indent=2, sort_keys=True)
-    result = api.m.step('config', [])
     config_lines = config_string.splitlines()
-    result.presentation.logs['Bisect job configuration'] = config_lines
+    step.presentation.logs['Bisect job configuration'] = config_lines
 
   @property
   def api(self):