Implemented locally:

def _git_word_diff(oldtext: str, newtext: str, context: int = 0) -> None:
    with tempfile.TemporaryDirectory() as tmp_dir:
        old_path = Path(tmp_dir) / 'old.txt'
        new_path = Path(tmp_dir) / 'new.txt'
        old_path.write_text(oldtext, encoding='utf-8')
        new_path.write_text(newtext, encoding='utf-8')
        subprocess.run(
            [
                'git', 'diff', '--no-index',
                f'--unified={context}',
                '--color=always',
                '--color-words=.',
                '--',
                str(old_path),
                str(new_path),
            ],
            check=False,
        )
 
pywikibot.showDiff = _git_word_diff

We cannot assume that git bash is always preinstalled. Pywikibot can be installed from nightly dump or installed as package from pypi.

Change #1231794 had a related patch set uploaded (by Xqt; author: Xqt):

[pywikibot/core@master] IMPR: Improve PatchManager

https://gerrit.wikimedia.org/r/1231794

@vitaly-zdanevich: I've changed the showDiff() behaviour; could you please check it if it looks better now.

CI tests may fail in the current state because the by_letter comparison has a breaking change but this doesn't care a lot because that feature is not used within the framework.

could you please check it if it looks better now.

still bad diff :(

In T415376#11550883, @Xqt wrote:

We cannot assume that git bash is always preinstalled. Pywikibot can be installed from nightly dump or installed as package from pypi.

Maybe use git diff when its available?

In T415376#11551502, @vitaly-zdanevich wrote:

could you please check it if it looks better now.

still bad diff :(

I have a different behaviour. What is the command line you are using?

PYTHONPATH=/tmp/core/ ./globustut_fix.py

and my script prints Pywikibot version 11.0.0.dev10

Change #1232593 had a related patch set uploaded (by Xqt; author: Xqt):

[pywikibot/core@master] textlib: Add textlib.Content.as_list method

https://gerrit.wikimedia.org/r/1232593

Change #1232667 had a related patch set uploaded (by Xqt; author: Xqt):

[pywikibot/core@master] IMPR: Use textlib.extract_sections for showing text differences

https://gerrit.wikimedia.org/r/1232667

But a site parameter must be used with pywikibot.showDiff like:

pywikibot.showDiff(text, new_text, site=page.site)

The diff on your screenshot shows many unchanged lines :(

In T415376#11552038, @vitaly-zdanevich wrote:

The diff on your screenshot shows many unchanged lines :(

You are right. A better approach would be to

• replace line feeds inside tables and templates and around them with a marker
• use splitlines() to split the text in smaller parts as before
• replace the markers with line feeds
• proceed as usual

Change #1233173 had a related patch set uploaded (by Xqt; author: Xqt):

[pywikibot/core@master] textlib: add replace_within helper to replace text only inside tags

https://gerrit.wikimedia.org/r/1233173

@vitaly-zdanevich: Would this be ok:

url-status= is not changed :(

And space to the new line: would it be possible to use some symbol for that? For example ↵
U+21B5 DOWNWARDS ARROW WITH CORNER LEFTWARDS