python 2：

在python2里，用assert判断一个字典是否是另一个字典的子集并不能直接用in, not in，只能用set的issubset
比较方法：

a = {'x': 1, 'y': 2, 'z': 3}
b = {'x': 1}
c = {'y': 2, 'd': 3}

assert six.viewitems(b) in six.viewitems(a)
# 直接比较会出错
"""
Traceback (most recent call last):
  File "/home/python/Desktop/zxc/others/six_test.py", line 21, in <module>
    assert six.viewitems(b) in six.viewitems(a)
AssertionError
"""
# 可以用：
assert set(six.viewitems(b)).issubset(set(six.viewitems(a)))

unittest的assert：

a = {'x': 1, 'y': 2, 'z': 3}
b = {'x': 1}
c = {'y': 2, 'd': 3}


class TestZ(unittest.TestCase):

    def test_compare(self):

        print six.viewitems(a)
        print six.viewitems(b)
        # self.assertTrue(set(six.viewitems(b)).issubset(six.viewitems(a)))
        self.assertFalse(set(six.viewitems(c)).issubset(six.viewitems(a)))


if __name__ == '__main__':
    unittest.main()