test_xrange.py 文件源码

def assert_iterators_equal(self, xs, ys, test_id, limit=None):
        # check that an iterator xs matches the expected results ys,
        # up to a given limit.
        if limit is not None:
            xs = itertools.islice(xs, limit)
            ys = itertools.islice(ys, limit)
        sentinel = object()
        pairs = itertools.izip_longest(xs, ys, fillvalue=sentinel)
        for i, (x, y) in enumerate(pairs):
            if x == y:
                continue
            elif x == sentinel:
                self.fail('{}: iterator ended unexpectedly '
                          'at position {}; expected {}'.format(test_id, i, y))
            elif y == sentinel:
                self.fail('{}: unexpected excess element {} at '
                          'position {}'.format(test_id, x, i))
            else:
                self.fail('{}: wrong element at position {};'
                          'expected {}, got {}'.format(test_id, i, y, x))