Yes – pip should have a dry-run option, to indicate what would happen in a complex situation. It is dangerous when running pip install downgrades packages without asking you. We need some way to ask what would happen if we run pip install -r requirements.txt without laboriously searching thru all the requirements and comparing them to the currently installed ones.
It looks like setup.py used to have a dry-run. Folks are asking for it elsewhere.
Some progress in that direction can be found here:
- Dry Run for Python Pip | BackSlasher
- nvie/pip-tools: A set of tools to keep your pinned Python dependencies fresh.
Update: Activity continues on the official bug related to this: Add `pip install –dry-run` or similar, to get resolution result · Issue #53 · pypa/pip. It is blocked on the development of the dependency resolver, which is nearing completion