'Verify that all hooks which have not been verified against
a hook specification are optional, otherwise raise PluginValidationError'

def check_pending(self):

    for name in self.hook.__dict__:
        if (name[0] != '_'):
            hook = getattr(self.hook, name)
            if (not hook.has_spec()):
                for hookimpl in (hook._wrappers + hook._nonwrappers):
                    if (not hookimpl.optionalhook):
                        raise PluginValidationError(('unknown    hook    %r    in    plugin    %r' % (name, hookimpl.plugin)))
