sliding_window() recipe: Raise ValueError for non-positive window sizes. Add more tests.

[rhettinger]

The existing recipe was giving bogus results for n=0:

>>> list(sliding_window('ABCDEFG', 0))
[(), ('A',), ('B',), ('C',), ('D',), ('E',), ('F',), ('G',)]

• Fix and simplify code
• Add better error checking
• Add more extensive tests

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📚 Documentation preview 📚: https://cpython-previews--105403.org.readthedocs.build/

[miss-islington]

Thanks @rhettinger for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[miss-islington]

Sorry, @rhettinger, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 423459be2f0b6d007e5f235f39d80044cb099faf 3.11

[bedevere-bot]

GH-105405 is a backport of this pull request to the 3.12 branch.

[pochmann]

The existing recipe was giving bogus results for n=0:

>>> list(sliding_window('ABCDEFG', 0))
[(), ('A',), ('B',), ('C',), ('D',), ('E',), ('F',), ('G',)]

That would mean that deque violates maxlen=0. Are you sure? That would be a bug in it's own right.

I was getting [(), (), (), (), (), (), (), ()] as expected. Btw I once was about to suggest what you did here, but realized it would stop supporting the n=0 case. I thought the old longer code was like that in order to support n=0. Was that not the case? I find unnecessarily breaking n=0 disappointing. It used to correspond to for example 'ABCDEFG'.count('') simply returning 8, just like the recipe used to yield 8 empty windows.