'Check the parsers are valid.'

def testParsersRetrieval(self):

    for processor in parsers.Parser.classes.values():
        if ((not hasattr(processor, 'output_types')) or (not isinstance(processor.output_types, (list, tuple)))):
            raise parsers.ParserDefinitionError(('Missing    output_types    on    %s' % processor))
        for output_type in processor.output_types:
            if (output_type not in rdfvalue.RDFValue.classes):
                raise parsers.ParserDefinitionError(('Parser    %s    has    an    output    type    that    is    an    unknown    type    %s' % (processor, output_type)))
