feat: provide a noninteractive way to check clone state

Is your feature request related to a problem? Please describe.

There is no noninteractive way to check if template clones are up-to-date with the latest changes in the template. Likewise, there is no way to figure out if a configuration drift had occurred.

Describe the solution you’d like

I’d like Copier to provide mechanism(s) to test those 2 states.

Describe alternatives you’ve considered

Using Cruft which supports this functionality in 2 ways, with:

• a check command: only check if the project is up to date
• a diff command with an --exit-code: check if the project has drifted

Additional context

I’d like to schedule a clone state check with a CI service.

[yajo]

If that’s how Cruft works, then it makes me happy because I see Copier makes a big improvement.

In Copier, updating compares the original template with the latest version and extracts the diff, then applies it into your project. This is more powerful because it lets you modify any files and still get updates if your modifications don’t conflict with how the template has evolved.

Only when both the template and the generated project have evolved differently the same code, Copier will leave *.rej files around with them.

What you want is something I call a “recopy”, which ignores such evolution and just reapplies the latest template on top of your current project, just reusing the answers. Recopies are not supported on Copier 5, but for v6 they’re already in master, so nothing to do here.

[fdaguin]

Fair enough, thanks for the clarification and for your time!