Python unittest assertAlmostEqual()用法及代碼示例

assertAlmostEqualPython中的()是一個單元測試庫函數，用於單元測試中以檢查兩個給定的值是否幾乎相等。此函數將使用五個參數作為輸入，並根據斷言條件返回布爾值。

此函數通過計算差值，四舍五入到給定的小數位數(默認為7)，然後與零進行比較，以檢查第一和第二個近似相等。

如果提供了增量而不是位置，則第一和第二之間的差異必須小於或等於增量。

用法： assertAlmostEqual(first, second, places=7, message=None, delta=None)

參數：assertAlmostEqual()接受以下說明的三個參數：

first：第一個輸入值(整數)
second：第二個輸入值(整數)
places：近似的小數位
message：作為測試消息失敗時顯示的消息的字符串語句。
delta：近似的增量值

下麵列出了兩個不同的示例，它們說明了給定assert函數的正麵和負麵測試案例：

例：

Python3

# test suite 
import unittest 
  
  
class TestStringMethods(unittest.TestCase):
    # negative test function to test if values are almost equal with place 
    def test_negativeWithPlaces(self):
        first = 4.4555
        second = 4.4566
        decimalPlace = 3
        # error message in case if test case got failed 
        message = "first and second are not almost equal."
        # assert function() to check if values are almost equal 
        self.assertAlmostEqual(first, second, decimalPlace, message) 
  
    # positive test function to test if values are almost equal with place 
    def test_positiveWithPlaces(self):
        first = 4.4555
        second = 4.4566
        decimalPlace = 2
        # error message in case if test case got failed 
        message = "first and second are not almost equal."
        # assert function() to check if values are almost equal 
        self.assertAlmostEqual(first, second, decimalPlace, message) 
  
    # negative test function to test if values are almost equal with delta 
    def test_negativeWithDelta(self):
        first = 4.4555
        second = 4.4566
        delta = 0.0001
        # error message in case if test case got failed 
        message = "first and second are not almost equal."
        # assert function() to check if values are almost equal 
        self.assertAlmostEqual(first, second, None, message, delta) 
  
    # positive test function to test if values are almost equal with delta 
    def test_positiveWithDelta(self):
        first = 4.4555
        second = 4.4566
        delta = 0.002
        # error message in case if test case got failed 
        message = "first and second are not almost equal."
        # assert function() to check if values are almost equal 
        self.assertAlmostEqual(first, second, None, message, delta) 
  
  
if __name__ == '__main__':
    unittest.main()

輸出：

FF..
======================================================================
FAIL:test_negativeWithDelta (__main__.TestStringMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/2c36bbd2c940a6c7b81a901ebfdd2ad8.py", line 34, in test_negativeWithDelta
    self.assertAlmostEqual(first, second, None, message, delta)
AssertionError:4.4555 != 4.4566 within 0.0001 delta:first and second are not almost equal.

======================================================================
FAIL:test_negativeWithPlaces (__main__.TestStringMethods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/2c36bbd2c940a6c7b81a901ebfdd2ad8.py", line 14, in test_negativeWithPlaces
    self.assertAlmostEqual(first, second, decimalPlace, message)
AssertionError:4.4555 != 4.4566 within 3 places:first and second are not almost equal.

----------------------------------------------------------------------
Ran 4 tests in 0.001s

FAILED (failures=2)

參考：https：//docs.python.org/3/library/unittest.html

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注：本文由純淨天空篩選整理自Shivam.Pradhan大神的英文原創作品 Python unittest – assertAlmostEqual() function。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。