Some sugar to ease dict subset checking.

dict-subset-sugar.py

def dict_contains_subset(superset, subset):
    for key, value in subset.iteritems():
        if key not in superset or superset[key] != value:
            return False
    else:
        return True


class SupersetDict(dict):
    def __contains__(self, other):
        if isinstance(other, dict):
            return dict_contains_subset(self, other)
        else:
            return super(SupersetDict, self).__contains__(other)


superset = SupersetDict


if __name__ == '__main__':
  print {'a': 1} in {'a': 1}
  # TypeError: unhashable type: 'dict'

  print {'a': 1} in superset({'a': 1})
  # True

  print {'a': 1} in superset({'a': 1, 'b': 2})
  # True

  print {'a': 1} in superset({'b': 2})
  # False