Vanishing requirements

[nazavode]

I've stumbled upon an issue that causes reqwire to drop previously added dependencies to a requirement .in. Steps to reproduce:

bash-3.2$ mkdir test
bash-3.2$ cd test
bash-3.2$ reqwire init
created /Users/fmontag/test/requirements/src
created /Users/fmontag/test/requirements/lck
created /Users/fmontag/test/requirements/src/docs.in
created /Users/fmontag/test/requirements/src/main.in
created /Users/fmontag/test/requirements/src/qa.in
created /Users/fmontag/test/requirements/src/test.in
bash-3.2$ reqwire add sqlalchemy
Collecting sqlalchemy
Installing collected packages: sqlalchemy
Successfully installed sqlalchemy-1.1.5
saving requirement(s) to main
bash-3.2$ cat requirements/src/main.in
# -*- mode: requirementstxt -*-
# vim: set ft=requirements
# Generated by reqwire on Sun Feb 26 20:12:35 2017
--index-url https://pypi.python.org/simple
SQLAlchemy==1.1.5

Ok, at this point let's add another dependency to main.in:

bash-3.2$ reqwire add sqlalchemy-utils
Collecting sqlalchemy-utils
Requirement already satisfied: six in /Users/fmontag/venv/lib/python3.6/site-packages (from sqlalchemy-utils)
Requirement already satisfied: SQLAlchemy>=1.0 in /Users/fmontag/venv/lib/python3.6/site-packages (from sqlalchemy-utils)
Installing collected packages: sqlalchemy-utils
Successfully installed sqlalchemy-utils-0.32.12
saving requirement(s) to main
bash-3.2$ cat requirements/src/main.in
# -*- mode: requirementstxt -*-
# vim: set ft=requirements
# Generated by reqwire on Sun Feb 26 20:13:03 2017
--index-url https://pypi.python.org/simple
SQLAlchemy-Utils==0.32.12

The first one just vanishes, adding a second dependency drops the first. Maybe it is just because sqlalchemy-utils pulls in sqlalchemy as a dependency but both of them are top level dependencies for my project so I was expecting to have both of them pinned in main.in.

[darvid]

This is expected behavior for now, as SQLAlchemy is a dependency of SQLAlchemy-Utils. I'm not totally convinced that top-level dependencies should be preserved by default, so for now I've made it configurable with the preserve_toplevel environment configuration.

$ reqwire add sqlalchemy
$ REQWIRE_PRESERVE_TOPLEVEL=true reqwire add sqlalchemy-utils

It's a bit of a hack, as it intersects the initial requirements to the resolved requirements, which were resolved (with pip-tools) through the initial + specified requirements anyway. This results in the version of the common requirements being changed to the resolved version. In your example, SQLAlchemy's version changes to SQLAlchemy==1.1.5,>=1.0.

I think this option should be sufficient for now, let me know if it works for you or if you have any other concerns. (Released as 0.8 btw)

[nazavode]

I got your point, preserving all top level dependencies even if they are not actually top level anymore (just like in this case), could lead to some conflicting behaviour, but I have no clear idea about this at the moment.
So for now thank you so much for the great support!