Django 在运行测试时不创建测试数据库

Question

我在 Django 文档中读到将创建一个空白数据库用于测试。我是 Django 的新手，所以我几乎没有改变 setting.py 和当前使用的 Sqlite 数据库。但是，当我运行 python manage.py test 时，Django 一直告诉用户已经存在，所以我尝试更改 TestCase 中创建的用户的用户名，再次运行测试，发现新的用户是在现有数据库中创建的。测试文件如下:

class UserTestCase(unittest.TestCase):
    def setUp(self):
        admin = User.objects.create(username="admin", password="1")
        user1 = User.objects.create(username="user1", password="1")
        user2 = User.objects.create(username="user2", password="1")
        admin.following.add(user1)
        admin.followers.add(user2)

    def test_users_count(self):
        self.assertEqual(User.objects.count()==3)

我的模型如下:

class User(AbstractUser):
    followers = models.ManyToManyField('self', related_name="following", symmetrical=False, through='Follow', through_fields=('followee', 'follower'))
    
    def __str__(self):
        return f"{self.username}"

    def serialize(self):
        return {
            "id": self.id,
            "username": self.username,
        }

class Follow(models.Model):
    followee = models.ForeignKey(
        'User',
        on_delete=models.CASCADE,
        related_name='+'
    )
    follower = models.ForeignKey(
        'User',
        on_delete=models.CASCADE,
        related_name='+'
    )

    def clean(self, *args, **kwargs):
        if self.follower__id == self.followee__id:
            raise ValidationError('Can not follow self.')
        return super().clean(*args, **kwargs)
    
    class Meta:
        constraints = [
            models.UniqueConstraint(fields=['follower', 'followee'], name='follow_once'),
            models.CheckConstraint(check=~Q(follower=F('followee')), name='not_follow_self')
        ]

编辑:下面是我运行 python manage.py test

时的输出

(env_web) PS C:\Users\HL94NVT\Programming\web_development\project4> python manage.py test
System check identified no issues (0 silenced).
EE
======================================================================
ERROR: test_following_count (network.tests.UserTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute       
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: UNIQUE constraint failed: network_user.username

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\HL94NVT\Programming\web_development\project4\network\tests.py", line 21, in setUp
    admin = User.objects.create(username="admin1", password="1")
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\query.py", line 447, in create
    obj.save(force_insert=True, using=self.db)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\contrib\auth\base_user.py", line 67, in save
    super().save(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 754, in save
    force_update=force_update, update_fields=update_fields)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 792, in save_base
    force_update, using, update_fields,
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 895, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 935, in _do_insert
    using=using, raw=raw,
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\query.py", line 1254, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\sql\compiler.py", line 1397, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: network_user.username

======================================================================
ERROR: test_users_count (network.tests.UserTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: UNIQUE constraint failed: network_user.username

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\HL94NVT\Programming\web_development\project4\network\tests.py", line 21, in setUp
    admin = User.objects.create(username="admin1", password="1")
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\query.py", line 447, in create
    obj.save(force_insert=True, using=self.db)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\contrib\auth\base_user.py", line 67, in save
    super().save(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 754, in save
    force_update=force_update, update_fields=update_fields)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 792, in save_base
    force_update, using, update_fields,
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 895, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\base.py", line 935, in _do_insert
    using=using, raw=raw,
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\query.py", line 1254, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\models\sql\compiler.py", line 1397, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HL94NVT\Programming\web_development\env_web\lib\site-packages\django\db\backends\sqlite3\base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: network_user.username

----------------------------------------------------------------------
Ran 2 tests in 0.063s

Answer 1

根据文档，使用 django.test.TestCase 而不是 unittest.TestCase 有帮助 https://docs.djangoproject.com/en/3.1/topics/testing/overview/

If your tests rely on database access such as creating or querying models, be sure to create your test classes as subclasses of django.test.TestCase rather than unittest.TestCase.

Using unittest.TestCase avoids the cost of running each test in a transaction and flushing the database, but if your tests interact with the database their behavior will vary based on the order that the test runner executes them. This can lead to unit tests that pass when run in isolation but fail when run in a suite.