Python: Unable to import global variable initialized in setUp method from init file

Question

I have a package with testing modules and inside the init file I have a setUp method with some operations. These operations are executed correctly before any unit test in the package's modules run. Inside the setUp method I'd like to initialize a global variable and then access it from other modules of the package. But this doesn't work.

# TestPackage/__init__.py
def setUp():
    global spec_project
    core_manager = get_core_manager()
    spec_project = core_manager.get_spec()

#TestPackage/test_module.py
from TestPackage import spec_project
import unittest

class TestRules(unittest.TestCase):
    def setUp(self):
        spec_project.get_new_device()

Like this I get an

ImportError: cannot import name spec_project

If I initialize the spec_project variable outside of the setUp method in the init file I can have access to it but its content is not changed after the operations in the setUp method.

# TestPackage/__init__.py
spec_project = None
def setUp():
    global spec_project
    core_manager = get_core_manager()
    spec_project = core_manager.get_spec()

#TestPackage/test_module.py
from TestPackage import spec_project
import unittest

class TestRules(unittest.TestCase):
    def setUp(self):
        spec_project.get_new_device()

Like this I get an

AttributeError: 'NoneType' object has no attribute 'get_new_device'

How can initialize the spec_project variable inside the setUp method of the init file and still have access to it from other module in the package?

Answer 1

It looks like setUp() isn't being called, but if you are certain that it is, then it could be the way that you are importing TestPackage. Try importing like this:

#TestPackage/test_module.py
import TestPackage
import unittest

class TestRules(unittest.TestCase):
    def setUp(self):
        TestPackage.spec_project.get_new_device()

The setUp() method has to be called before you use the global. This same thing should apply to the second way you tried. But again, that is assuming that setUp is run. You can alias TestPackage if you feel it is necessary, or you should be able to import it if it is defined outside the method.

Since you are explicitly importing it, it is likely trying to make a copy of it, which isn't possible, since it is inside of the setUp() body.