Issue 6757 - Improved diff output for similar strings.

[piotrhm]

This pull request implements suggested approach for issue #6757. Visualization:

[bluetech]

I don't have an opinion on this feature (yet?), but left some minor comments/suggestions.

[bluetech]

Also, note that the "linting" CI check failed, due to formatting errors. You can fix it by running tox -e linting (or running black manually). You also check the logs and apply the necessary changes manually.

[nicoddemus]

Thanks a lot @piotrhm for working on this, we appreciate it.

Besides the comments left by @bluetech and me, could you please also add a test for this functionality? I like the cow example. 😁

[nicoddemus]

Thanks a lot @piotrhm, great work!

[nicoddemus]

@bluetech would you like to take a second look?

[nicoddemus]

Also, @piotrhm meanwhile could you rebase and solve the conflict there? Thanks!

[piotrhm]

Done. Thanks a lot @nicoddemus!

[nicoddemus]

@bluetech gentle ping for a final review. 👍

[bluetech]

I left some code comments. Some high level comments as well:

• I'm confused about the desired behavior. The PR title says "Improve diff output for similar strings"; the changelog says "if the texts differ significantly (more than 30% of lines and more than 4 lines)", the actual code triggers the new behavior on s.ratio() >= 0.30 and max(nlines_left, nlines_right) >= 5 (that is 30% similarity). Logically the changelog sounds right (I think), but the code does the opposite.

• I believe that using screen_width as done here is problematic because the explanation can be indented, e.g. in the new "drill down" mode and possibility other cases, in which case the =s will overflow and look funny. Somehow the indentation needs to be account for (though I don't think the code is built for that), or a solution that doesn't rely on screen width should be used.

[bluetech]

Instead of adding get_terminal_reporter() to Config and a screen_width property, it will be better to use config.get_terminal_writer().fullwidth.

[bluetech]

Just a note, moving code around makes it harder to review, because it breaks the diff view, so best to do it separately.

I guess this is a relevant comment for this PR 😄

[bluetech]

IIUC str.center can take care of most of this. Also can you explain why the margin (10) is needed?

Suggested change

	def _text_header(header: str, screen_width: int, margin: int = 10) -> List[str]:
	hlength = len(header)
	lines = [
	"=" * int((screen_width - hlength - margin) / 2)
	+ header
	+ "=" * int((screen_width - hlength - margin) / 2)
	]
	if screen_width % 2 != 0:
	lines[-1] += "="
	return lines
	explanation += _text_header(" ACTUAL ", screen_width)
	explanation += list(left.split("\n"))
	explanation += _text_header(" EXPECTED ", screen_width)
	explanation += list(right.split("\n"))
	explanation += [
	" ACTUAL ".center(screen_width - 10, "="),
	*left.split("\n"),
	" EXPECTED ".center(screen_width - 10, "="),
	*right.split("\n"),
	]

[gnikonorov]

Hi @piotrhm . If this PR is meant to close an issue, could you please update the description as described here so that the linked issue may autoclose?

[bluetech]

Hi @piotrhm,

First of all we would like to thank you for your time and effort on working on this, the pytest team deeply appreciates it.

We noticed it has been awhile since you have updated this PR, however. pytest is a high activity project, with many issues/PRs being opened daily, so it is hard for us maintainers to track which PRs are ready for merging, for review, or need more attention.

So for those reasons we think it is best to close the PR for now, but with the only intention to cleanup our queue, it is by no means a rejection of your changes. We still encourage you to re-open this PR (it is just a click of a button away) when you are ready to get back to it.

Again we appreciate your time for working on this, and hope you might get back to this at a later time!