Question

如何使用Factory对象覆盖django模型，以避免命中数据库。

models.py

from django.db import models

class ApplicationType(models.Model):
    """
    Types of applications available in the system/
    """
    title = models.CharField(max_length=30)

    def __str__(self):
        return self.title

utils.py

from .models import ApplicationType

self.base_details = {}

def get_application_type(self, value):
 """
 Get types of applications. When successful it Populates the 
 self.base_details with an application_type key

 Args:
     value (object): value to be parsed

 Returns:
     bool:  True when value is ok, Else false

 Raises:
 """
 item_name = "Application Type"
 self.base_details['application_type'] = None
 try:
     if value:
         try:
             result = ApplicationType.objects.get(title=value)  # <== How do I avoid hitting this DB object?
             self.base_details['application_type'] = result.id
             return True
         except ApplicationType.DoesNotExist:
             self.error_msg = "Invalid Value: {}".format(item_name)
             return False
     else:
         self.error_msg = "Blank Value: {}".format(item_name)
         return False
 except:
     raise

因此，为了测试，我创建了一个ApplicationType工厂

tests.py

import factory
import pytest
application_types = ['Type 1', 'Type 2']

class ApplicationTypeFactory(factory.Factory):
    class Meta:
        model = ApplicationType

    title = "application_type_title"


@pytest.mark.django_db()
def test_get_application_type_populates_dict_when_value_provided_exists_in_database(self):
    """Populates base_details dict when value is found in database"""
    for entry in application_types:
        application_type = ApplicationTypeFactory.build(title=entry)
        assert self.base_info_values.get_application_type(entry) == True
        assert self.base_info_values.base_details["application_type"] is not None

因此，您将如何编写一个测试，避免在代码中间的ApplicationType.objects.get()查询中访问数据库？我可以将“模型”作为参数传递给函数吗？这是一个好的设计吗？

您可以自由地为应用程序/功能提供替代结构，尤其是为了在这种情况下进行更好的测试。

正在运行Python3.5，pytest-django和factory_boy

Answer 1

您可以修补对数据库的调用，以返回您设置的预定义值。在你的情况下，你可以做这样的事情：

import factory
import pytest
from unittest.mock import Mock, patch
application_types = ['Type 1', 'Type 2']
@pytest.mark.django_db()
@patch('ApplicationType.objects.get')
def test_get_application_type_populates_dict_when_value_provided_exists_in_database(self, db_mocked_call):
    """Populates base_details dict when value is found in database"""
    mocked_db_object = {'id': 'test_id'}
    db_mocked_call.return_value = mocked_db_object
    for entry in application_types:
        application_type = ApplicationTypeFactory.build(title=entry)
        assert self.base_info_values.get_application_type(entry) == True
        assert self.base_info_values.base_details["application_type"] is not None

我建议您检查pytest.parametrize以避免在测试中使用for循环，请在此处详细了解：http://doc.pytest.org/en/latest/parametrize.html

在您的示例中，测试可能如下所示：

@pytest.mark.django_db()
@pytest.mark.parametrize("entry", ['Type 1', 'Type 2'])
@patch('ApplicationType.objects.get')
def test_get_application_type_populates_dict_when_value_provided_exists_in_database(self, db_mocked_call, entry):
    """Populates base_details dict when value is found in database"""
    mocked_db_object = {'id': 'test_id'}
    db_mocked_call.return_value = mocked_db_object
    application_type = ApplicationTypeFactory.build(title=entry)
    assert self.base_info_values.get_application_type(entry) == True
    assert self.base_info_values.base_details["application_type"] is not None

如何避免在此测试用例中访问数据库

1 个答案: