Thanks @stephen and @mikael

I moved the test folder (as below - there was a higher app folder also which I have now shown here):

app/tests/test_basic.py
app/app/core.py

and included this in the test_*.py scripts:

module_path = os.path.join(os.path.dirname(sys.path[0]), 'app') sys.path.append(module_path) import core

which allows for dynamic determination of the appropriate path.

Unfortunately, this sits above an import statement and PEP 8 doesn't like it...oh well.