feat(geometry): define supported boundaries and add regression tests … - #42

Description

This pull request defines and documents the supported boundary contract of LineIntersection and introduces focused regression boundary tests covering degenerate zero-length segments, interior crossings, T-junctions, touching endpoints, extreme coordinates, and null precondition handling.

Related Issue

Fixes: #2

Type of Change

• Tests
• Documentation
• Bug Fix
• New Feature
• UI/UX Improvement
• Performance Improvement
• Refactoring / Maintenance
• CI/CD

Changes Made

• Documented the supported boundary contract in src/main/java/com/thealgorithms/geometry/LineIntersection.java detailing 32-bit integer coordinate bounds, degenerate point handling, interior and boundary intersections, collinear overlaps, and non-null preconditions.
• Expanded src/test/java/com/thealgorithms/geometry/LineIntersectionTest.java with tests on both sides of each boundary:
  • Smallest valid input ((0, 0) degenerate points intersecting, alongside disjoint degenerate points).
  • Ordinary input (standard interior crossing at (3.0, 3.0)).
  • T-junction boundary (endpoint lying on segment interior vs. separated by 1 unit).
  • Touching endpoint boundary (non-collinear vertex touching vs. shifted gap).
  • Extreme coordinate domain boundary testing coordinates up to ±1,000,000.
  • Null input precondition check asserting NullPointerException.
  • Private constructor reflection contract.
• Added automated boundary check runner work/R45-T002/check.py and saved verification evidence in work/R45-T002/results.json and work/R45-T002/evidence.md.

Screenshots / Recordings

N/A (backend geometry utility and test changes only; non-UI)

Testing

All changes have been validated locally using JDK 21 and Maven:

• mvn test -Dtest=LineIntersectionTest (Tests run: 14, Failures: 0, Errors: 0, Skipped: 0)
• mvn checkstyle:check (0 Checkstyle violations)
• python3 work/R45-T002/check.py (All checks and boundary assertions passed successfully)

Checklist

• I have tested my changes locally.
• I have added or updated tests, if needed.
• I have updated documentation, if needed.
• I have followed the project's coding guidelines.
• I have run the relevant tests and checks.
• I have addressed previous review feedback, if applicable.
• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms include a corresponding test class that validates their functionality.
• All new code adheres to repository style conventions and passes mvn checkstyle:check.

Additional Notes

• Precondition lines establishing input requirements are explicitly cited in both the test methods and work/R45-T002/evidence.md.
• Automated check runner can be verified anytime with python3 work/R45-T002/check.py.