Shyamli Bakale — R45-T020: Strengthen the tests of encrypt (Autokey.java) [src/main/java/com/thealgorithms/ciphers/Autokey.java] #20

Student: Shyamli Bakale

Task: R45-T020 · 10 of 10
Repository: https://github.com/S-AI-Projects/TheAlgorithms-Java
Assigned working branch: student/e26b07f0813

Goal

Work on src/main/java/com/thealgorithms/ciphers/Autokey.java. Prove that a regression test can detect a plausible one-line mistake in encrypt. 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 encrypt from src/main/java/com/thealgorithms/ciphers/Autokey.java. 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 src/main/java/com/thealgorithms/ciphers/Autokey.java, especially encrypt 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/R45-T020/check.py as a focused runner that executes the new checks and propagates failures. Native check to incorporate: mvn test (JDK 21 as specified in pom.xml); use JUnit in the corresponding src/test/java package. Record the actual command and nonzero test count.
5. Create the checks specified below and run python3 work/R45-T020/check.py. Save inputs, expected versus actual results and tool versions in work/R45-T020/; a check must exit non-zero when an assertion fails.
6. Commit the repository change on branch R45-T020; prepare a PR to the organisation fork explaining the result and linking the checks. Keep each task independently reviewable. Remove work/R45-T020/ from a later upstream branch.

Done when

☐ The checked behavior is tied to encrypt in src/main/java/com/thealgorithms/ciphers/Autokey.java; every assertion has an explicit expected value.
☐ Use the smallest valid input and one ordinary input for encrypt from src/main/java/com/thealgorithms/ciphers/Autokey.java. 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.