Python generates SystemError when trying to import a module into another module

问题

I have a file calc.py where I have methods for basic calculations.Now I create another file (in the same directory) called test_calc.py for unittesting the methods in calc.py file.But when I try to run test_calc.py either through command line using

python3 -m unittest test_calc.py

or since I have included name == "main"

python3 test_calc.py

or try to run it directly through the IDE,I get an error that says

from . import calc
SystemError: Parent module '' not loaded, cannot perform relative import

Below is the screenshot of my project structure

Below is the screenshot of how I import the calc.py file and it accepts the import

This is the code in test_calc.py file which unitests the methods defined in calc.py file

import unittest
from . import calc

class TestCalc(unittest.TestCase):
    def test_add(self):
        result = calc.add(5,2)
        self.assertEqual(result,7)

if __name__ == "__main__":
    unittest.main()

When I run the above code, Python thows error.What is going wrong?

回答1:

You can refer to "Relative imports in Python 3", which suggests, amongst other alternative

python3 -m unittest mypackage.test_calc.py

Try at least to not have a space in your 'unittest module' folder.