用于引發不同例外的函式的單元測驗

提供了以下代碼

from typing import Union, Tuple
import unittest


def split_value_and_unit(inp_value: Union[str, int, float]) -> Tuple[float, str]:
    unit = ''
    value: float
    if (isinstance(inp_value, int) or isinstance(inp_value, float)):
        value = float(inp_value)
    else:
        # get rid of = sign at the beginning of string
        str_value = inp_value
        if (inp_value.startswith('=')):
            str_value = inp_value[1:]
        if ('*' in inp_value):
            sep_index = str_value.index('*')
            try:
                value = float(str_value[:sep_index])
            except ValueError:
                raise Exception(f'Expected a string containing a float number and a unit. "{str(inp_value)}" does not fulfil this requirement')
            unit = str_value[sep_index   1:]
        else:
            try:
                value = float(str_value)
            except ValueError:
                raise Exception(f'Expected a string containing a float number and a unit. "{str(inp_value)}" does not fulfil this requirement')
    return (value, unit)


class TestX(unittest.TestCase):
    def test_split_value_and_unit(self):
        # self.assertRaisesRegex(Exception, r'Expected a string containing a float number and a unit. "_0" does not fulfil this requirement', lambda: split_value_and_unit('_0'))
        self.assertRaisesRegex(Exception, 'Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement', lambda: split_value_and_unit('_1 e16'))

我本來希望單元測驗通過。但是運行會coverage run -m unittest -v test.x回傳以下輸出：

test_split_value_and_unit (test.x.TestX) ... FAIL

======================================================================
FAIL: test_split_value_and_unit (test.x.TestX)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "c:\Users\klosemic\Documents\SVN_wc\trunk\Tools\ng_scripts\orchid_ng\test\x.py", line 24, in split_value_and_unit
    value = float(str_value)
ValueError: could not convert string to float: '_1 e16'

During handling of the above exception, another exception occurred:

Exception: Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\Users\klosemic\Documents\SVN_wc\trunk\Tools\ng_scripts\orchid_ng\test\x.py", line 33, in test_split_value_and_unit
    self.assertRaisesRegex(Exception, 'Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement', lambda: split_value_and_unit('_1 e16'))
AssertionError: "Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement" does not match "Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement"

----------------------------------------------------------------------
Ran 1 test in 0.002s

FAILED (failures=1)

如果我交換測驗例外的兩行（所以如果我通過“_0”而不是“_1e 16”）測驗通過。
所以我的問題是，為什么“_1e 16”與測驗用例的“_0”不同？尤其是當我在函式中明確處理 ValueError 時（如果這不是很好的風格不是這里的重點）。

提前致謝

uj5u.com熱心網友回復：

self.assertRaisesRegex將正則運算式作為第二個引數。由于您的正則運算式包含通配符 ( .) 和量詞 ( )，因此您的字串不再匹配。

有關更多詳細資訊，請參閱https://regex101.com/r/GPwpTV/1與https://regex101.com/r/Z9O7tP/1。

您正在尋找的正則運算式需要轉義這些字符如下：

r'Expected a string containing a float number and a unit\. "_1\ e16" does not fulfil this requirement'

沒有它，量詞 將匹配1一次，然后沒有任何匹配的文字 。

完整代碼如下：

from typing import Union, Tuple
import unittest


def split_value_and_unit(inp_value: Union[str, int, float]) -> Tuple[float, str]:
    unit = ''
    value: float
    if (isinstance(inp_value, int) or isinstance(inp_value, float)):
        value = float(inp_value)
    else:
        # get rid of = sign at the beginning of string
        str_value = inp_value
        if (inp_value.startswith('=')):
            str_value = inp_value[1:]
        if ('*' in inp_value):
            sep_index = str_value.index('*')
            try:
                value = float(str_value[:sep_index])
            except ValueError:
                raise Exception(f'Expected a string containing a float number and a unit. "{str(inp_value)}" does not fulfil this requirement')
            unit = str_value[sep_index   1:]
        else:
            try:
                value = float(str_value)
            except ValueError:
                raise Exception(f'Expected a string containing a float number and a unit. "{str(inp_value)}" does not fulfil this requirement')
    return (value, unit)


class TestX(unittest.TestCase):
    def test_split_value_and_unit(self):
        # self.assertRaisesRegex(Exception, r'Expected a string containing a float number and a unit. "_0" does not fulfil this requirement', lambda: split_value_and_unit('_0'))
        self.assertRaisesRegex(Exception, r'Expected a string containing a float number and a unit\. "_1\ e16" does not fulfil this requirement', lambda: split_value_and_unit('_1 e16'))

或者import re，re.escape('Expected a string containing a float number and a unit. "_1 e16" does not fulfil this requirement')如果您不想擔心總是轉義特殊字符，則可以將其用作模式。

標籤：蟒蛇-3.x 正则表达式 单元测试

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