python - 如何对 ValidationError 进行单元测试并断言使用了正确的代码？

Question

我有一个带有 ValidationError 的模型约束:

class MyModel(models.Model)
    title = models.CharField()
      
    def clean(self):
        error_dict = {}
        if self.title='invalid_title':
                 error_dict['title'] = ValidationError(
                         'Title is invalid', code='invalid_title_code')
        
        if error_dict:
                 raise ValidationError(error_dict)

我想对这个 ValidationError 进行单元测试, 但我该如何测试 code是正确的？例如:

def test_title_invalid(self):

     with self.assertRaises(ValidationError) as cm: 
          MyModel.objects.create(title='invalid_title')
     
     exception = cm.exception

     # Test the key exists
     self.assertTrue(hasattr(exception, 'error_dict'))
     self.assertIn('title', exception.error_dict)

     # Test the message exists
     self.assertIn('Title is invalid', exception.messages)

     # Test the code exists
     self.assertIn('invalid_title_code', exception.code)

在 self.assertIn('invalid_title_code', exception.code) 之前一切正常，结果为 AttributeError表示'ValidationError' object has no attribute 'code'

在 django.core.exceptions.ValidationError 的 django 源代码中看来，如果你通过 dict object，不添加code属性:

class ValidationError(Exception):
    """An error while validating data."""
    def __init__(self, message, code=None, params=None):
        super().__init__(message, code, params)

        if isinstance(message, dict):
            self.error_dict = {}
            for field, messages in message.items():
                if not isinstance(messages, ValidationError):
                    messages = ValidationError(messages)
                self.error_dict[field] = messages.error_list
 
        else:
            self.message = message
            self.code = code
            self.params = params
            self.error_list = [self]

这是问题的原因吗？

Answer 1

这是一个嵌套异常，您可以通过以下方式访问它:

exception = cm.exception
self.assertTrue(hasattr(exception, 'error_dict'))
self.assertIn('title', exception.error_dict)
title_exceptions = <b>exception.error_dict['title']</b>
self.assertEqual(1, len(title_exceptions))
title_exception = <b>title_exceptions[0]</b>
self.assertEqual('invalid_title_code', <b>title_exception.code</b>)