Python unittest assertIsInstance()用法及代码示例

assertIsInstancePython中的()是单元测试库函数，用于单元测试中以检查对象是否为给定类的实例。此函数将使用三个参数作为输入，并根据断言条件返回布尔值。如果对象是给定类的实例，它将返回true，否则返回false。

用法： assertIsInstance(object, className, message)

参数：assertIsInstance()接受以下说明的三个参数：

object：作为给定类的实例检查的对象
className：对象实例要比较的类名
message：作为测试消息失败时显示的消息的字符串语句。

下面列出了两个不同的示例，它们说明了给定assert函数的正面和负面测试案例：

示例1：否定测试用例

Python3

# test suite 
import unittest 
  
# test class 
  
  
class Myclass:
    x = 5
  
  
class Myclass2:
    x = 6
  
  
class TestClass(unittest.TestCase):
    # test function to test whether obj is instance of class 
    def test_negative(self):
        objectName = Myclass() 
        # error message in case if test case got failed 
        message = "given object is not instance of Myclass."
        # assertIsInstance() to check if obj is instance of class 
        self.assertIsInstance(objectName, Myclass2, message) 
  
  
if __name__ == '__main__':
    unittest.main()

输出：

F
======================================================================
FAIL:test_negative (__main__.TestStringMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/a2e9f97d79f7d8c1fbd00c4df704d402.py", line 22, in test_negative
    self.assertIsInstance(objectName, Myclass2, message)
AssertionError:<__main__.Myclass object at 0x7f1e9bead0b8> is not an instance of <class '__main__.Myclass2'>:given object is not instance of Myclass.

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (failures=1)

示例2：正测试用例

Python3

# test suite 
import unittest 
  
# test class 
class Myclass:
    x = 5
  
  
class TestClass(unittest.TestCase):
    # test function to test whether obj is instance of class 
    def test_positive(self):
        objectName = Myclass() 
        # error message in case if test case got failed 
        message = "given object is not instance of Myclass."
        # assertIsInstance() to check if obj is instance of class 
        self.assertIsInstance(objectName, Myclass, 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

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注：本文由纯净天空筛选整理自Shivam.Pradhan大神的英文原创作品 Python unittest – assertIsInstance() function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。