Tarun Y — R50-T030: Strengthen the tests of PermutationinString (PermutationinString.js) [Dynamic-Programming/Sliding-Window/PermutationinString.js] #30

Student: Tarun Y

Task: R50-T030 · 10 of 10
Repository: https://github.com/S-AI-Projects/TheAlgorithms-JavaScript
Assigned working branch: student/e26b07f0633

Goal

Work on Dynamic-Programming/Sliding-Window/PermutationinString.js. Prove that a regression test can detect a plausible one-line mistake in PermutationinString. Use the fixture and invariant: Preserve the documented output type, shape, ordering and input-mutation behavior; compare fresh equivalent inputs under controlled external state. Fixture: Use the smallest valid input and one ordinary input for PermutationinString from Dynamic-Programming/Sliding-Window/PermutationinString.js. Write the literal inputs and independently calculated expected outputs in the tests before editing the implementation. The check must name the source line establishing each precondition.

Steps

1. Read Dynamic-Programming/Sliding-Window/PermutationinString.js, especially PermutationinString near line 15. Record its public inputs, result, mutation behavior and any external dependencies before changing it.
2. In a temporary copy, alter one boundary comparison, accumulation or return condition relevant to the algorithm.
3. Find a valid input for which the original and mutant differ; independently establish the correct output and reduce the input.
4. Implement work/R50-T030/check.py as a focused runner that executes the new checks and propagates failures. Native check to incorporate: run the repository test script in non-watch mode after installing from its lockfile; for browser-only code use a browser test instead of plain Node. Record the actual command and nonzero test count.
5. Create the checks specified below and run python3 work/R50-T030/check.py. Save inputs, expected versus actual results and tool versions in work/R50-T030/; a check must exit non-zero when an assertion fails.
6. Commit the repository change on branch R50-T030; prepare a PR to the organisation fork explaining the result and linking the checks. Keep each task independently reviewable. Remove work/R50-T030/ from a later upstream branch.

Done when

☐ The checked behavior is tied to PermutationinString in Dynamic-Programming/Sliding-Window/PermutationinString.js; every assertion has an explicit expected value.
☐ Use the smallest valid input and one ordinary input for PermutationinString from Dynamic-Programming/Sliding-Window/PermutationinString.js. Write the literal inputs and independently calculated expected outputs in the tests before editing the implementation. The check must name the source line establishing each precondition.
☐ Existing supported behavior and the public interface are preserved unless a failing regression demonstrates and documents a defect.
☐ The original passes and the mutant fails the same named assertion for a semantic reason.
☐ The final implementation contains no mutation or test-only branch.

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.