'@param reason: A string explaining why the test is marked \'todo\'
@param errors: An iterable of exception types that the test is
expected to raise. If one of these errors is raised by the test, it
will be trapped. Raising any other kind of error will fail the test.
If L{None} is passed, then all errors will be trapped.'

def __init__(self, reason, errors=None):

    self.reason = reason
    self.errors = errors
