'Assert that all objects watched for survival have survived.'

def _assertTruesurvival(self):

    gc.collect()
    dead = []
    for ((id_, repr_), ref) in self._survivors.items():
        if (ref() is None):
            dead.append(repr_)
    if dead:
        self.fail(('%d    objects    should    have    survived    but    have    been    destroyed:    %s' % (len(dead), ',    '.join(dead))))
