Python assert斷言

根據Python 官方文檔解釋(https://docs.python.org/3/reference/simple_stmts.html#assert), "Assert statements are a convenient way to insert debugging assertions into a program".

 

一般的用法是：

assert condition

用來讓程序測試這個condition，如果condition為false，那么raise一個AssertionError出來。邏輯上等同於：

if not condition:
    raise AssertionError()

比如如下的例子：

>>> assert 1==1
>>> assert 1==0
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    assert 1==0
AssertionError
>>> assert True
>>> assert False
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    assert False
AssertionError
>>> assert 3<2
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    assert 3<2
AssertionError