类型错误：strptime() 参数 1 必须是 str，而不是 None

Question

I'm new in Python. I have a util.py file to check the value of datetime. I writed a test case for it with value is None. But I got error strptime() argument 1 must be str, not None . Would someone please tell me how to fix it? Thank you.

My util.py :

from datetime import date, datetime
import traceback
import time
from analyzer.analyzerlogging import setup_stopwatch, setup_logger


def validate_date(logger, val, parameter_name, date_format, date_format_info):
    """ Check if val is the date with correct format, then return the date
    """
    _val = None
    try:
        _val = datetime.strptime(val, date_format)
    except ValueError:
        msg = f"Invalid value {val} of parameter {parameter_name}. {parameter_name.capitalize()} should be at format '{date_format_info}'"
        logger.error(msg)
        raise Exception(msg)
    return _val

My test case :

import unittest
from analyzer.util import validate_date
from datetime import date
import datetime
from analyzer.analyzerlogging import setup_logger


class TestUtilValidateDate(unittest.TestCase):

#val is None and date_format_info is YYYY/MM/DD HH:mm:ss
    def test_UT_UTIL_VALIDATE_DATE_005(self):
        try:
            validate_date(self.logger, None, 'param_name', '%Y/%m/%d %H:%M:%S', 'YYYY/MM/DD HH:mm:ss')
        except Exception as e:
            result = "Invalid value None of parameter param_name. Param_name should be at format 'YYYY/MM/DD HH:mm:ss'"
            self.assertEqual(str(e),result)

Error :

test_UT_UTIL_VALIDATE_DATE_005 (test_util_validate_date.TestUtilValidateDate) ... FAIL
NoneType: None

======================================================================
FAIL: test_UT_UTIL_VALIDATE_DATE_005 (test_util_validate_date.TestUtilValidateDate)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "c:\Users\duongnb\Documents\SVN\trunk\src\Analyzer\toshiba\yieldnews\ut\test_util_validate_date.py", line 44, in test_UT_UTIL_VALIDATE_DATE_005
    validate_date(self.logger, None, 'param_name', '%Y/%m/%d %H:%M:%S', 'YYYY/MM/DD HH:mm:ss')
TypeError: strptime() argument 1 must be str, not None

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\Users\duongnb\Documents\SVN\trunk\src\Analyzer\toshiba\yieldnews\ut\test_util_validate_date.py", line 47, in test_UT_UTIL_VALIDATE_DATE_005
    self.assertEqual(str(e),result)
AssertionError: 'strptime() argument 1 must be str, not None' != "Invalid value None of parameter param_na[52 chars]:ss'"
- strptime() argument 1 must be str, not None
+ Invalid value None of parameter param_name. Param_name should be at format 'YYYY/MM/DD HH:mm:ss'


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

FAILED (failures=1)

Answer 1

The unittest has worked correctly in your code - it indicates your try/except is not capturing the correct exception. Change your exception to TypeError and it will be caught and the message returned.

You should use self.assertRaisesMesssage if your aim is to check the expected error and error message that passing in None as arg1 produces.

mock_val = None
parameter_name = 'Foo'
date_format_info = 'YYYY/MM/DD HH:mm:ss'
expected_msg = f"Invalid value {mock_val} of parameter {parameter_name}. {parameter_name.capitalize()} should be at format '{date_format_info}'"

with self.assertRaisesMessage(TypeError, expected_msg):
    validate_date(self.logger, mock_val, parameter_name, '%Y/%m/%d %H:%M:%S', date_format_info)