Feature: pip-sync --dry-run should return a non-zero exit code if changes were to occur

[graingert]

What's the problem this feature will solve?

I'm looking to add a pre-commit hook to check the environment is up to date

-   repo: local
    hooks:
    -   id: pip-sync
        name: pip-sync check
        entry: pip-sync --dry-run
        language: system
        always_run: true
        pass_filenames: false

Describe the solution you'd like

$ pip-sync --dry-run
Would install:
  numpy==1.18.5
$ $?
2

Alternative Solutions

various | awk stuff

Additional context

NA

[francisbrito]

Hello @atugushev, @graingert. Is this change being worked on already? If not, is it OK if I write a PR for this feature?

[atugushev]

Hello @francisbrito,

Feel free to pick this up 👍

[atugushev]

Hello @graingert,

That sounds reasonable! Thanks for the issue.

[francisbrito]

Hello @atugushev,

Just a quick heads-up: the PR for this is #1172. Please let me know if you have any comments regarding it.

[graingert]

Amazing thanks @francisbrito and @atugushev !

[francisbrito]

You're welcome @graingert. Thanks for the opportunity!