Feature request: flag for exiting 1 if changes proposed

[Goorzhel]

Similar to:

❯ black --help | grep -A4 -- '--check'
  --check                         Don't write the files back, just return the
                                  status. Return code 0 means nothing would
                                  change. Return code 1 means some files would
                                  be reformatted. Return code 123 means there
                                  was an internal error.

[fangpenlin]

Hi @Goorzhel, thanks for the suggestion. I think this feature won't be too hard to implement, but could you share the scenarios where this comes handy? Usually I would love to learn the actual scenarios before adding new features so that maybe there's a better way to do it.

[Goorzhel]

I use bean-black as a pre-commit hook, and when I see it's made changes I have to abort my commit, git add them, and try again. Having the formatter exit 1 automates the "abort commit" part.

(EDIT: I realized while writing that paragraph that I should actually be using format-on-write, but I haven't set it up yet. My point about bean-black being useful as a pre-commit hook stands.)

[fangpenlin]

I see. I assume you're running beancount-black from hooks/pre-commit directly right? Currently we have pre-commit hooks ready for use:

https://github.com/LaunchPlatform/beancount-black/blob/master/.pre-commit-hooks.yaml

One can write a .pre-commit-config.yaml with content like

repos:
  - repo: https://github.com/LaunchPlatform/beancount-black
    rev: 1.0.0
    hooks:
      - id: beancount-black

then run

pre-commit install

to make it works. It does the file change check and aborting commit for you automatically. Would you prefer to use pre-commit instead or is there any particular reason you would rather use raw git pre-commit hook?

[Goorzhel]

I hadn't seen that, nor am I familiar with pre-commit-the-framework, but I'll try both and report here later.

And yes, I have a script in .git/hooks/pre-commit

#!/usr/bin/env -S bash -e

ag '^#!.*python' bin -l | xargs black -q --check

read -ra changed_bc_files < <(git diff --cached --name-only --diff-filter=ACM \
  | grep beancount$ | paste -sd " " )

if [ "${#changed_bc_files[@]}" -gt 0 ]; then
  bean-black -n "${changed_bc_files[@]}"
fi

[Goorzhel]

pre-commit is pretty cool! Consider me one of today's lucky ten thousand.

❯ echo -e "; uhhhhh\n\n\n\n\n\n" > uhh.beancount
❯ git add !$ && git commit -am uhhhh
alejandra............................................(no files to check)Skipped
beancount-black..........................................................Failed
- hook id: beancount-black
- files were modified by this hook

INFO:beancount_black.main:Processing file uhh.beancount
INFO:beancount_black.formatter:Calculate column width
INFO:beancount_black.formatter:Collecting
INFO:beancount_black.main:done

black................................................(no files to check)Skipped
❯ git diff
diff --git a/uhh.beancount b/uhh.beancount
index 10d1da1..9020a8e 100644
--- a/uhh.beancount
+++ b/uhh.beancount
@@ -1,7 +1 @@
 ; uhhhhh
-
-
-
-
-
-