Doctest and relative imports

Question

I'm having trouble using doctest with relative imports. The simple solution is just to get rid of the relative imports. Are there any others?

Say I have a package called example containing 2 files:

example/__init__.py

"""
This package is entirely useless.
>>> arnold = Aardvark()
>>> arnold.talk()
I am an aardvark.
"""

from .A import Aardvark

if __name__ == "__main__":
    import doctest
    doctest.testmod()

example/A.py

class Aardvark(object):
    def talk(self):
        print("I am an aardvark.")

If I now attempt

python example/__init__.py

then I get the error

Traceback (most recent call last):
  File "example/__init__.py", line 8, in <module>
    from .A import Aardvark
ValueError: Attempted relative import in non-package

I would get rid of the relative imports, many Python style guides strongly discourage them, most forbid them. — Jason Scheirer, Oct 28 '10 at 21:27

score 20 · Accepted Answer · answered Oct 28 '10 at 21:32

Create another file my_doctest_runner.py:

if __name__ == "__main__":
    import doctest
    import example
    doctest.testmod(example)

Execute my_doctest_runner.py to run doctests in example/__init__.py:

$ python2.7 my_doctest_runner.py
**********************************************************************
File "/tmp/example/__init__.py", line 4, in example
Failed example:
    arnold.talk()
Expected:
    I am an aaardvark.
Got:
    I am an aardvark.
**********************************************************************
1 items had failures:
   1 of   2 in example
***Test Failed*** 1 failures.

Thanks for the answer. In the end I've ended up changing the relative import to an absolute one, (from example.A import Aadvark) based on Jason Scheirer's comment. — Ben Reynwar, Oct 29 '10 at 03:22

score 3 · Answer 2 · answered Jun 26 '22 at 21:29

Pytest's --doctest-modules flag takes care of relative imports:

$ ls example/
A.py  __init__.py
$ pytest --doctest-modules example
==================== test session starts ====================
...

example/__init__.py .                                 [100%]

===================== 1 passed in 0.03s =====================

score 0 · Answer 3 · answered Mar 09 '23 at 11:09

0

As of pytest 6.0.0, importlib is a valid import mode. Using that solved the problem for me.

pytest --import-mode=importlib

answered Mar 09 '23 at 11:09

Lorenz Walthert

4,414
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score -1 · Answer 4 · answered Oct 28 '10 at 21:21

-1

Just do

from A import Aardvark

answered Oct 28 '10 at 21:21

pyfunc

65,343
15
148
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10

well, I am afraid this breaks python 3 compatibility. – chfw Nov 08 '14 at 23:25
1

While this code may answer the question, it is better to explain how to solve the problem and provide the code as an example or reference. Code-only answers can be confusing and lack context. – Robert Columbia May 20 '18 at 20:26

Doctest and relative imports

4 Answers4