测试抽象模型 - django 2.2.4 / sqlite3 2.6.0

Question

我正在尝试使用 django 2.2.4/sqlite3 2.6.0/python 3.6.8 测试一些简单的抽象混合。

目前，我在使用架构编辑器从测试数据库中删除模型时遇到问题。

我有以下测试用例：

from django.test import TestCase
from django.db.models.base import ModelBase
from django.db import connection


class ModelMixinTestCase(TestCase):
    """
    Test Case for abstract mixin models.
    """
    mixin = None
    model = None

    @classmethod
    def setUpClass(cls) -> None:
        # Create a real model from the mixin
        cls.model = ModelBase(
            "__Test" + cls.mixin.__name__,
            (cls.mixin,),
            {'__module__': cls.mixin.__module__}
        )

        # Use schema_editor to create schema
        with connection.schema_editor() as editor:
            editor.create_model(cls.model)

        super().setUpClass()

    @classmethod
    def tearDownClass(cls) -> None:
        # Use schema_editor to delete schema
        with connection.schema_editor() as editor:
            editor.delete_model(cls.model)

        super().tearDownClass()

可以这样使用：

class MyMixinTestCase(ModelMixinTestCase):
    mixin = MyMixin

    def test_true(self):
        self.assertTrue(True)

这确实允许创建和测试模型。问题是，在

ModelMixinTestCase.tearDownClass

中，

connection.schema_editor()

无法禁用在

django.db.backends.sqlite3.base

中使用以下命令完成的约束检查：

    def disable_constraint_checking(self):
        with self.cursor() as cursor:
            cursor.execute('PRAGMA foreign_keys = OFF')
            # Foreign key constraints cannot be turned off while in a multi-
            # statement transaction. Fetch the current state of the pragma
            # to determine if constraints are effectively disabled.
            enabled = cursor.execute('PRAGMA foreign_keys').fetchone()[0]
        return not bool(enabled)

这会导致

__enter__

中的

DatabaseSchemaEditor

出现异常：django.db.backends.sqlite3.schema

因此，基于所有这些，我假设我们处于原子上下文中，但我目前不确定退出该上下文并删除模型的最干净的方法是什么。

Answer 1

因此，经过一番挖掘和测试后，似乎最好让 django 的

    def __enter__(self):
        # Some SQLite schema alterations need foreign key constraints to be
        # disabled. Enforce it here for the duration of the schema edition.
        if not self.connection.disable_constraint_checking():
            raise NotSupportedError(
                'SQLite schema editor cannot be used while foreign key '
                'constraint checks are enabled. Make sure to disable them '
                'before entering a transaction.atomic() context because '
                'SQLite does not support disabling them in the middle of '
                'a multi-statement transaction.'
            )
        return super().__enter__()

正常关闭事务，然后从测试数据库中删除模型。本质上我们只是首先调用

TestCase

而不是最后一个。模型混合测试用例

因为这是一个有用的课程，我将发布完整的课程供其他人复制/粘贴。

super().tearDownClass()

使用示例1

class ModelMixinTestCase(TestCase):
    """
    Test Case for abstract mixin models.
    Subclass and set cls.mixin to your desired mixin.
    access your model using cls.model.
    """
    mixin = None
    model = None

    @classmethod
    def setUpClass(cls) -> None:
        # Create a real model from the mixin
        cls.model = ModelBase(
            "__Test" + cls.mixin.__name__,
            (cls.mixin,),
            {'__module__': cls.mixin.__module__}
        )

        # Use schema_editor to create schema
        with connection.schema_editor() as editor:
            editor.create_model(cls.model)

        super().setUpClass()

    @classmethod
    def tearDownClass(cls) -> None:
        # allow the transaction to exit
        super().tearDownClass()

        # Use schema_editor to delete schema
        with connection.schema_editor() as editor:
            editor.delete_model(cls.model)

        # close the connection
        connection.close()

使用示例2

class MyMixinTestCase(ModelMixinTestCase):
    mixin = MyMixin

    def test_true(self):
        self.assertTrue(True)

Answer 2

但是当在具有相同模型的不同测试用例上重用 mixin 时，我遇到了警告：

class SortableModelMixinTestCase(ModelMixinTestCase):
    mixin = SortableModelMixin

    def setUp(self) -> None:
        self.objects = [self.model.objects.create(pk=i) for i in range(10)]

    def test_order_linear(self) -> None:
        i = 1
        for item in self.objects:
            self.assertEqual(i, item.sortable_order)
            i += 1

我通过检查模型是否已在应用程序中注册来解决这个问题：

RuntimeWarning: Model '<model_name>' was already registered. Reloading models is not advised as it can lead to inconsistencies, most notably with related models.