pip install local package to target directory

Question

I have a Python library that is published to PyPI. Before pushing each new version of the library, I want to test it by upgrading a sample application to use the new version.

The suggested method to do this is to work in "development mode" using the -e (--editable) flag:

$ pip install -e <my package root>

And this does indeed install the package into my global environment.

However, my sample program is written for Google App Engine, which requires that all third-party libraries be copied into an application-specific folder (./lib in my case). I normally install packages here by using the -t (--target) option to pip:

$ pip install -t lib/ <package>

However, it appears that the -e and -t options are not compatible, and my attempts to install my local, unpublished library to a specified target folder by using both flags together fail.

How can I test my library package by installing it in a custom directory before publishing?

Answer 1

For one-time testing of a new package, installing directly from the local filesystem seems to be the best bet:

$ cd /my/sample/application
$ pip install -t lib /my/local/package

This install won't stay in sync as I make further changes to the local package (as it would if I were to use pip install --editable), but I can live without that for this use case.

I couldn't get @pbaranay's answer to work because of the way pip install -e uses "egg-info" files that apparently are not understood/traversed by GAE's dev_appserver.py script. The suggestion to create a virtualenv and symlink it to lib (rather than installing packages directly to lib with -t) is a good one, though.