Class instance fails isinstance check

Question

Hi

I have some code on my CI failing (local runs do not fail). The problem is that class instance fails isinstance() check.

Code:

File: main.py

...
def get_variables_context(self: SuperController, **kwargs):
    from main import MyController
    self: MyController

    print(f"type(self) is {type(self)} (it {'IS' if (isinstance(self, MyController)) else 'IS NOT'} a subclass of MyController)")
    _super = super(MyController, self).get_variables_context(**kwargs) or dict()
    _super.update(result)
    return _super

File: my_options.py

type(self) is <class '__main__.SomeController'> (it IS NOT a subclass of SomeController
Traceback (most recent call last):
  File "main.py", line 24, in <module>
    SomeController.main(**params)
  File "/builds/RND/my/rcv-nginx/tests/nginx_tests/flow.py", line 391, in main
    _tests_suite, _, _ = self.prepare()
  File "/builds/RND/my/rcv-nginx/tests/nginx_tests/flow.py", line 359, in prepare
    context['variables_context'] = self.get_variables_context(**context)
  File "/builds/RND/my/tests/integration/my_options.py", line 81, in get_variables_context
    _super = super(SomeController, self).get_variables_context(**kwargs) or dict()
TypeError: super(type, obj): obj must be an instance or subtype of type

Got output and error:

 type(self) is <class '__main__.SomeController'> (it IS NOT a subclass of SomeController Traceback (most recent call last): File "main.py", line 24, in <module> SomeController.main(**params) File "/builds/RND/my/rcv-nginx/tests/nginx_tests/flow.py", line 391, in main _tests_suite, _, _ = self.prepare() File "/builds/RND/my/rcv-nginx/tests/nginx_tests/flow.py", line 359, in prepare context['variables_context'] = self.get_variables_context(**context) File "/builds/RND/my/tests/integration/my_options.py", line 81, in get_variables_context _super = super(SomeController, self).get_variables_context(**kwargs) or dict() TypeError: super(type, obj): obj must be an instance or subtype of type 

Answer 1

I've found the solution while investigating the root cause.

In the local run, ...

I actually call the python unittest which then calls main.py which then creates a class MyController which then calls my_options.py , and the class is added to the loaded module 'main' . Then, MyController.get_variables_context asks for the module 'main' , which is already loaded, then for the class MyController in that module, so the same type instance is returned and type check succeeds.

In the CI run, ...

I call directly main.py with the argument "test" (which should create a controller and run all tests from it via unittest), so the class MyController is created inside module __main__ . MyController.get_variables_context still asks for the MyController class in main.py , but the module 'main' is not loaded here, so python loads it, creates new class MyController , and then returns it.

So, basically the answer is ...

to move MyController from main.py to the other file, ie controller.py