Raised meaningful error for short peptide stretch

[spyke7]

Fixes #5046

Changes made in this Pull Request:

• Added a block for raising value error inside init in dssp.py
• Checked the length of ag.residues, and just raised a simple value error message showing the minimum required residues

PR Checklist

• Issue raised/referenced?
• Tests updated/added?
• Documentation updated/added?
• package/CHANGELOG file updated?
• Is your name in package/AUTHORS? (If it is not, add it!)

Developers Certificate of Origin

I certify that I can submit this code contribution as described in the Developer Certificate of Origin, under the MDAnalysis LICENSE.

---

📚 Documentation preview 📚: https://mdanalysis--5163.org.readthedocs.build/en/5163/

[spyke7]

@orbeckst @marinegor please check this, and do I need to add extra tests for this? and also codecov is failing, so I think it would be better if I add tests right?

and please tell me what to write in CHANGELOG, cause I'm confused about the format.... :-)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.72%. Comparing base (bbcef1b) to head (8d0d67b).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5163      +/-   ##
===========================================
- Coverage    92.72%   92.72%   -0.01%     
===========================================
  Files          180      180              
  Lines        22472    22474       +2     
  Branches      3188     3189       +1     
===========================================
+ Hits         20837    20838       +1     
  Misses        1177     1177              
- Partials       458      459       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[IAlibay]

Please add:

1. Tests that trigger the error
2. Tests that check that the system passes with 6 residues (and that it returns correct results)
3. Update the docstring "Raises" section
4. Update relevant docs to make it clear that at least 6 residues are necessary
5. Update the changelog

[IAlibay]

Suggested change

	n_residues = len(ag.residues)
	MIN_RESIDUES = 5
	if n_residues < MIN_RESIDUES:
	raise ValueError(
	f"DSSP requires at least {MIN_RESIDUES} residues for secondary structure analysis, but only {n_residues} residue(s) were provided in the selection."
	)
	if len(ag.residues) < 6:
	raise ValueError(
	"DSSP requires at least 6 residues for secondary structure analysis, "
	f"but only {len(ag.residues)} residue(s) were provided in the selection."
	)

See the original issue "fewer than 6 residues" not 5.
Also there's no need to define one time use variables.

[spyke7]

ok, doing the changes!

[spyke7]

done

[IAlibay]

and please tell me what to write in CHANGELOG, cause I'm confused about the format.... :-)

Please look at the instructions in the changelog (

mdanalysis/package/CHANGELOG

Lines 6 to 13 in bbcef1b

	The rules for this file:
	* entries are sorted newest-first.
	* summarize sets of changes - don't reproduce every git log comment here.
	* don't ever delete anything.
	* keep the format consistent (79 char width, M/D/Y date format) and do not
	use tabs but use spaces for formatting
	* accompany each entry with github issue/PR number (Issue #xyz)
	* release numbers follow "Semantic Versioning" https://semver.org

), and try to add something. If something about the changelog is unclear, then ask us specifically about (edit: what is unclear).

[spyke7]

If something about the changelog is unclear, then ask us specifically about the.

ok