Python unittest – assertIsNone()函数

Python中的assertIsNone () 是一个 unittest 库函数，用于在单元测试中检查输入值是否为None 。该函数将两个参数作为输入，并根据断言条件返回一个布尔值。如果输入值等于 None， assertIsNone () 将返回 true，否则返回 false。

Syntax: assertIsNone(testValue, message)

Parameters: assertIsNone() accept two parameters which are listed below with explanation:

• testValue:  test variable as the input value to check equality with None
• message: a string sentence as a message which got displayed when the test case got failed.

下面列出了两个不同的示例，说明了给定断言函数的正负测试用例：

示例 1：否定测试用例

Python3

# unit test case
import unittest
  
class TestMethods(unittest.TestCase):
    # test function 
    def test_negative(self):
        firstValue = "geeks"
        # error message in case if test case got failed
        message = "Test value is not none."
        # assertIsNone() to check that if input value is none
        self.assertIsNone(firstValue, message)
  
if __name__ == '__main__':
    unittest.main()

输出：

F
======================================================================
FAIL: test_negative (__main__.TestMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "p1.py", line 14, in test_negative
    self.assertIsNone(firstValue, message)
AssertionError: 'geeks' is not None : Test value is not none.

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)

示例 2：正面测试用例

Python3

# unit test case
import unittest
  
  
class TestMethods(unittest.TestCase):
    # test function 
    def test_positive(self):
        firstValue = None
        # error message in case if test case got failed
        message = "Test value is not none."
        # assertIsNone() to check that if input value is none
        self.assertIsNone(firstValue, message)
  
if __name__ == '__main__':
    unittest.main()

输出：

.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

参考：https://docs。 Python.org/3/library/unittest.html