Repository navigation
Paulami Bhosle — R23-T053: Harden ciphers/porta_cipher.py against bad input #53
Description
Student: Paulami Bhosle
Task: R23-T053 · 3 of 10
Repository: https://github.com/S-AI-Projects/TheAlgorithms-Python
Assigned working branch: student/e26b07f0792
Goal
Find inputs that crash or silently give wrong answers, and make the code raise clear exceptions as CONTRIBUTING.md requires. No raises at all: probe non-letter keys, an empty key, lowercase/uppercase mixes and non-string input.
Steps
- Try at least 8 bad inputs (wrong type, empty, negative, None, huge, unusual characters) and record what happens to each.
- Decide the correct behaviour for each (raise ValueError/TypeError with a clear message, or handle it).
- Implement it and add a doctest for every new error path.
- Document the input contract in the docstring.
- Make the code change in the repository: ciphers/porta_cipher.py: validation for empty or non-letter keys and non-string input, with doctests. Re-run the automated check and the repo's own tests afterwards.
- Prepare the PR: on branch R23-T053, commit the code change plus your work/R23-T053/ evidence, put your findings in the PR description and open the PR against the org fork. For a later upstream PR, create a second branch containing only the code change (no work/ folder).
Done when
☐ PR table of ≥8 bad inputs to generate_table/encrypt/decrypt (empty key, digits in key, mixed case, non-string).
☐ ciphers/porta_cipher.py raises ValueError/TypeError with messages and doctests for each decided-invalid input (it had no raises).
☐ Existing 5 doctests pass (ciphers/porta_cipher.py).
Additional task guidance
Additional curated task guidance
Item:
ciphers/porta_cipher.py (103 lines; 5 doctests)
Task type:
Input validation
Code change (goes into the PR):
ciphers/porta_cipher.py: validation for empty or non-letter keys and non-string input, with doctests.
Automated check:
uv run pytest ciphers/porta_cipher.py
Prerequisites:
Linux/WSL2/Codespaces with uv (https://docs.astral.sh/uv/getting-started/installation/); run uv sync --group=test once – it installs the Python version CI uses (.python-version = 3.15t) and the test dependencies, about 1–2 GB
Upstream PR rules:
Follow CONTRIBUTING.md: type hints on every parameter/return, doctests for valid and erroneous input, snake_case file names, no duplicate of an existing implementation, no hand edits to DIRECTORY.md. CI (pytest with doctests, ruff) must pass – bots close PRs without tests or type hints. Keep work/ (benchmarks, notes, property tests) out of the upstream branch; put results in the PR description.
Source (pinned):
https://github.com/TheAlgorithms/Python/blob/574d100b7181956e9c8384552fd078165e4cc326/ciphers/porta_cipher.py
Change:
No change recorded
PR destination:
Preserved pilot guidance
Submission checklist
- Complete this task and its checks.
- Add the required evidence and link your pull request here.
- Select this S-AI-Projects fork as the PR base repository.
- Request instructor review.
Keep this PR focused on this task. Do not submit assignment PRs to the upstream repository.
Activity