This question is occasioned by instructions in the python guide for adding a project to sys path to use in tests, which do not seem to work unless I am misunderstanding the instructions
I have a directory structure for a python project like this
sample/a.py sample/b.py sample/c.py sample/__init__.py test/context.py test/test_something.py test/__init__.py docs
According to the python guide, I should create a test/context.py file and add this
import os
import sys
sys.path.insert(0, os.path.abspath('..'))
import sample
Then, in my test/test_something.py file, it says I can do this
from .context import sample
The guide says “This will always work as expected”.
but, when I cd into test and run
python -m unittest test_something
I get an error
ValueError: Attempted relative import in non-package
and the error message specifically refers to this: from .context import sample
Question: How can I add my sample package to the sys path correctly?
When answering, can you also clarify if the solution will handle absolute imports within the sample package. For example, my sample.a imports sample.b etc. When I had my tests structured a different way, I did an absolute import of sample.a, but since it has a relative import of from .b import Boo, it produced a similar error
Update
`File "/usr/local/lib/python2.7/runpy.py", line 162 in _run_module_as_main "__main__", fname, loader, pkg_name)
File "/usr/local/lib/python2.7/runpy.py", line 72, in _run_code exec code in run_globals
File "/usr/local/lib/python2.7/unittest/__main__.py", line 12, in module main(module=None)
File "/usr/local/lib/python2.7/unittest/main.py", line 94, in __init__ self.parseArgs(argv)
File "/usr/local/lib/python2.7/unittest/main.py", line 149 in parseArgs self.createTests()
File "/usr/local/lib/python2.7/unittest/main.py", line 158, in createTests self.module)
File "/usr/local/lib/python2.7/unittest/loader.py", line 130, in loadTestsFromNames suites = [self.loadTestsFromName(name,module) for name in names]
File "/usr/local/lib/python2.7/unittest/loader.py", line 91, in loadTestsFromName module = __import__('-'.join(parts_copy))
File "test_something.py", line 8, in module from .context import sample
Update
if I run the following command from root directory
python -m unittest test
It says , “Ran 0 tests in 0.000s”
If, as was suggested in the comments by @cuongnv, I run this from root directory
python -m unittest test/test_something.py
or this (without the file extension)
python -m unittest test/test_something
It says “Import by filename is not supported”
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Answer
Question: How can I add my sample package to the sys path correctly?
You’re doing it the right way, but you missed declaring your folder to be a package. Try solution of Christian, it should work.
Your path is stored in sys.path. By doing this:
sys.path.insert(0, os.path.abspath('..'))
You’re telling your python to add upper folder (of current file) into your path. As sys.path is a list, you can using other methods of list like insert, append…
In your case, you’re inserting your upper dir at top of the path list.
See:
In [1]: import sys In [2]: sys.path Out[2]: ['', '/usr/local/bin', '/usr/lib/python3.4', '/usr/lib/python3.4/plat-x86_64-linux-gnu', '/usr/lib/python3.4/lib-dynload', '/usr/local/lib/python3.4/dist-packages', '/usr/lib/python3/dist-packages', '/usr/local/lib/python3.4/dist-packages/IPython/extensions', '/home/cuong/.ipython'] In [3]: sys.path.insert(0, '/tmp/foo') In [4]: sys.path Out[4]: ['/tmp/foo', **<-- on top** '', '/usr/local/bin', '/usr/lib/python3.4', '/usr/lib/python3.4/plat-x86_64-linux-gnu', '/usr/lib/python3.4/lib-dynload', '/usr/local/lib/python3.4/dist-packages', '/usr/lib/python3/dist-packages', '/usr/local/lib/python3.4/dist-packages/IPython/extensions', '/home/cuong/.ipython']
So, from here, when you have
import sample
your python will try to look in path to see if there is any sample package.
Unfortunately, it can’t find sample as you didn’t make it as a package because your forgot __init__.py in sample folder.
Hope my explanation would help you to understand and you can handle other situations different to this.