Why don't my unit tests run in Python?

Question

I have

myapp/
    __init__.py
    lib.py
    tests/
        lib_test.py

In lib_test.py I have:

import lib

When running from myapp:

python tests/lib_test.py

I get an error

ImportError: No module named lib

It's some sort of beginner error no doubt. However I can't figure out what is going wrong.

Jeff Tratner · Accepted Answer · 2013-06-08 09:38:42Z

5

When you try to do import lib like you have above, Python tries to find the import, starting with the directory you are in (so, for example, if you were right in the myapp directory, it would find lib.py and be able to import lib). However, when importing within a package (basically, anything with __init__.py) you should go towards using explicit package imports (like from myapp import lib) so that the python interpreter will know where to look. This also has the advantage of avoiding namespace collisions with lib (i.e., if you were in a different folder that had lib.py in it).

Bottom line: replace import lib with from myapp import lib and you'll be good.

edited Jun 8, 2013 at 9:38

answered Jun 8, 2013 at 9:08

Jeff Tratner

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1 Comment

Benjamin Hodgson Over a year ago

Personally, I have a preference for relative imports: from .. import lib. This requires an __init__.py file in the tests directory.

awesoon · Accepted Answer · 2013-06-08 07:46:50Z

1

You should add __init__.py file in tests/ directory.

edited Jun 8, 2013 at 7:46

awesoon

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answered Jun 8, 2013 at 7:45

Shreeyansh Jain

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2 Comments

Hoa Over a year ago

Thank you for the excellent suggestion. Unfortunately I'm still getting the same error

Shreeyansh Jain Over a year ago

Could you please try this "from myapp import lib" in lib_test.py file.

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