[eesmith]

It could, certainly. But

1) you don't have one black commit for every non-black commit, do you? Because the general best practice is to do like kuu suggested and have a specific black version as part of the development environment, with a pre-commit hook to ensure no random formatting gets introduced.

2) assuming 500 commits in your bisection, that's, what, about 9 compilations you'll need to do, so it will take you 9 hours to run. So even with a black commit after every human commit, that yes, 1 hour more, but it's also only 11% longer.

Even with only 10 non-black commits and 10 black commits, your average bisect time will only increase from 3.6 hours to 4.6 hours, or 30% longer.

I'm curious to know what project you are on with 1 hour build times and the regular need for hours-long bisection search, but where there isn't a common Python dev environment with a specific black version. Are you using ccache and/or distributed builds? If not, why isn't there a clear economic justification for improving your build environment? I mean, I assume developers need to build and test before commit, which means each commit is already taking an hour. Isn't that a waste of expensive developer time?

And, I assume it's not the black formatting changes which result in hour-long builds. If they do, could you explain how?

[bombolo]

As I said in other comments, if you try to force contributors to reproduce exactly your local setup, you will be left with no contributors. Which is why you set up a CI to run the tests… because people will most likely not.

As for build times, it was an extreme example. But even an extra step taking 5 extra minutes is very annoying to me…

[eesmith]

> if you try to force contributors to reproduce exactly your local setup, you will be left with no contributors. ...

That's not been my experience. To the contrary, having a requirements.txt means your contributors are more likely to have a working environment, as when your package depends on package X but the contributor has a 5-year-old buggy version of X, doesn't realize it, and it causes your program to do the wrong thing.

In any case, your argument only makes sense if no one on the project uses black or other code formatter. Even if you alone use it, odds are good that most of your collaborator's commits will need to be reformatted.

> .. an extra step taking 5 extra minutes ...

How do black reformatting changes cause an extra 5 minutes? What Python code base with only a couple of contributors and no need for a requirements.txt takes 5+ minutes to byte-compile and package the Python code, and why?

Adding 5 minutes to you build means your bisections are taking at least an hour, so it seems like focusing on black changes is the wrong place to look.

[bombolo]

> How do black reformatting changes cause an extra 5 minutes?

Did you even read my comments?

Black reformatting causes more steps in bisecting. It's quite easy that a test suite takes 5+ minutes.

[eesmith]

None of your comments mention running the full test suite, only build.

When I've used bisection, I've always had a targeted test that I was trying to fail, not the entire test suite. This is because the test suite at the time of that commit wasn't good enough to detect this failure. Otherwise it would have failed with that commit.

Instead, a new failure mode is detected, an automated test developed, and that used to probe the history to identify the commit.

Why are your bisections doing the full suite?

> Black reformatting causes more steps in bisecting

Yes, of course it does. But it's log2(n).

The worst-case analysis I did assumed there was a black commit after every human commit. This is a bad practice. You should be using black as a pre-commit hook, in which case only your new collaborator's commits will cause re-formats. And once they are onboard, you can explain how to use requirements.txt in a virtualenv.

If only 10% of the commits are black reformattings, which is still high!, then a bisection of 100 human commits (plus 10 black commits) goes from about 6.64 tests to 6.78 tests, which with a 5 minute test suite takes an additional 42 seconds.

If it's 3% then your bisection time goes up by 13 seconds.

If you are so worried about 13 seconds per bisection then how much time have you spent reducing the 5 minute test suite time? I presume you run your test suite before every commit, yes? Because if not, and you're letting CI run the test suite, then you're likely introducing more commits to fix breaking tests than you would have added via black, and taking the mental task switch hit of losing then regaining focus.

[bombolo]

> This is a bad practice. You should be using black as a pre-commit hook

I would reject such commits in review.

A human might add one or two items to a list and black might decide it's now too long, and make 1 line into 10 lines.

Now I have to manually compare the list item by item to figure out what has changed.

So I normally require formatting to be done in a separate commit, because I don't want to review the larger than necessary diffs that come out doing it within the same commit.

[eesmith]

> A human might add one or two items to a list and black might decide it's now too long, and make 1 line into 10 lines.

A human might add one or two items to a list, decide it's now too long, and make 1 line into 10 lines.

Including the same hypothetical first contributor you mentioned earlier, who you think will find using requirements.txt as being too big a barrier to entry.

Onboarding occurs either way.

I get that you don't like using black - and that's fine! I don't use black on my project either.

But it seems like you're trying to find some other reason to reject black, and constructing hypotheticals that don't make any sense.

Just say you don't like black's choices, and leave it at that.

[geysersam]

> if you try to force contributors to reproduce exactly your local setup

  python -m venv venv
  pip install -r requirements.txt

Do you consider that imposing? I assumed that was standard. Don't basically all Python projects in existence use something like it?