Add resilience in croc to a failed build (e.g. 0 stats generated)....

tools/code_coverage/croc.py

 #!/usr/bin/python2.4
 #
 # Copyright 2009, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #        * Redistributions of source code must retain the above copyright
@@ skipping 34 matching lines @@
 
 class CrocStatError(CrocError):
   """Error evaluating coverage stat."""
 
 #------------------------------------------------------------------------------
 
 
 class CoverageStats(dict):
   """Coverage statistics."""
 
+  # Default dictionary values for this stat.
+  DEFAULTS = { 'files_covered': 0,
+               'files_instrumented': 0,
+               'files_executable': 0,
+               'lines_covered': 0,
+               'lines_instrumented': 0,
+               'lines_executable': 0 }
+
   def Add(self, coverage_stats):
     """Adds a contribution from another coverage stats dict.
 
     Args:
       coverage_stats: Statistics to add to this one.
     """
     for k, v in coverage_stats.iteritems():
       if k in self:
         self[k] += v
       else:
         self[k] = v
 
+  def AddDefaults(self):
+    """Add some default stats which might be assumed present.
+
+    Do not clobber if already present.  Adds resilience when evaling a
+    croc file which expects certain stats to exist."""
+    for k, v in self.DEFAULTS.iteritems():
+      if not k in self:
+        self[k] = v
+
 #------------------------------------------------------------------------------
 
 
 class CoveredFile(object):
   """Information about a single covered file."""
 
   def __init__(self, filename, **kwargs):
     """Constructor.
 
     Args:
@@ skipping 315 matching lines @@
     # print the stats from just that subdir
 
     # Make sure the group exists
     if group not in self.tree.stats_by_group:
       if default is None:
         raise CrocStatError('Group %r not found.' % group)
       else:
         return default
 
     stats = self.tree.stats_by_group[group]
+    # Unit tests use real dicts, not CoverageStats objects,
+    # so we can't AddDefaults() on them.
+    if group == 'all' and hasattr(stats, 'AddDefaults'):
+      stats.AddDefaults()
     try:
       return eval(stat, {'__builtins__': {'S': self.GetStat}}, stats)
     except Exception, e:
       if default is None:
         raise CrocStatError('Error evaluating stat %r: %s' % (stat, e))
       else:
         return default
 
   def PrintStat(self, stat, format=None, outfile=sys.stdout, **kwargs):
     """Prints a statistic from the coverage object.
@@ skipping 297 matching lines @@
     html.Write()
 
   # Normal exit
   return 0
 
 
 #------------------------------------------------------------------------------
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))