Python Django测试在添加一个测试用例后未能安装夹具

我几乎开始怀疑Django应用程序的测试用例数量是否有限制，因此我需要您的帮助来找出如何避免这个问题，并在我的应用程序中对所有测试用例进行功能测试

我的Django v1.10.7应用程序有4个fixture测试用例，运行良好。一旦我添加了第五个带有fixture的测试用例，运行测试 连同

python3./manage.py测试myapp

开始导致一个随机的旧测试用例失败：

ERROR: setUpClass (myapp.tests.RandomOldTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 206, in _cursor
    return self.create_cursor()
  File "/usr/lib/python3/dist-packages/django/db/backends/postgresql/base.py", line 211, in create_cursor
    cursor = self.connection.cursor()
psycopg2.InterfaceError: connection already closed

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

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/test/testcases.py", line 1019, in setUpClass
    'database': db_name,
  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 130, in call_command
    return command.execute(*args, **defaults)
  File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 345, in execute
    output = self.handle(*args, **options)
  File "/usr/lib/python3/dist-packages/django/core/management/commands/loaddata.py", line 64, in handle
    self.loaddata(fixture_labels)
  File "/usr/lib/python3/dist-packages/django/core/management/commands/loaddata.py", line 104, in loaddata
    self.load_label(fixture_label)
  File "/usr/lib/python3/dist-packages/django/core/management/commands/loaddata.py", line 167, in load_label
    obj.save(using=self.using)
  File "/usr/lib/python3/dist-packages/django/core/serializers/base.py", line 201, in save
    models.Model.save_base(self.object, using=using, raw=True, **kwargs)
  File "/usr/lib/python3/dist-packages/django/db/models/base.py", line 824, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/usr/lib/python3/dist-packages/django/db/models/base.py", line 889, in _save_table
    forced_update)
  File "/usr/lib/python3/dist-packages/django/db/models/base.py", line 939, in _do_update
    return filtered._update(values) > 0
  File "/usr/lib/python3/dist-packages/django/db/models/query.py", line 654, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/usr/lib/python3/dist-packages/django/db/models/sql/compiler.py", line 1148, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/usr/lib/python3/dist-packages/django/db/models/sql/compiler.py", line 833, in execute_sql
    cursor = self.connection.cursor()
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 233, in cursor
    cursor = self.make_cursor(self._cursor())
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 206, in _cursor
    return self.create_cursor()
  File "/usr/lib/python3/dist-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/lib/python3/dist-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/usr/lib/python3/dist-packages/django/db/backends/base/base.py", line 206, in _cursor
    return self.create_cursor()
  File "/usr/lib/python3/dist-packages/django/db/backends/postgresql/base.py", line 211, in create_cursor
    cursor = self.connection.cursor()
django.db.utils.InterfaceError: Problem installing fixture '/home/lynoure/PycharmProjects/usertools2/useraccounts/fixtures/test-fixtures.json': connection already closed

新测试用例是什么似乎无关紧要，即使我用新名称复制了一个预先存在的测试，这种情况也会发生

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如果重要的话，这是在Debian Stable上，postgresql的版本是9.6+181，python3-psycopg2是2.6.2-1。

作为一种解决方法，可以标记一些测试用例，然后只运行不包含标记的测试：

from django.test import tag

@tag('trouble')
class TroubleTestCase(TestCase):
...

而要运行：

python3 ./manage.py test myapp --exclude-tag=trouble

之后必须单独运行这些测试：

python3 ./manage.py test myapp --tag=trouble

---

结果是如果你有两个

super().tearDownClass()

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您的代码中缺少，这就是您得到的症状。因此，如果这种情况发生在您身上，请检查您的测试用例是否有调用父类的tearDownClass。

似乎很想通过使用TransactionTestCase来“解决”这个问题，但是没有加载fixture，所以有些东西仍然会被破坏。serialized_rollback=True似乎没有任何区别parallel=1也没有区别