🧪 Add Unit Tests for Core Functions

## Description
Implement unit tests to ensure code reliability and prevent regressions.

## Tasks
- [ ] Set up pytest framework
- [ ] Write tests for core functions
- [ ] Achieve at least 70% code coverage
- [ ] Add GitHub Actions for automated testing
- [ ] Document testing procedures

## Expected Outcome
Automated tests that run on every commit.

## Skills Required
- Python testing (pytest)
- Unit testing concepts
- GitHub Actions

## Difficulty Level
🟡 Intermediate

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*Hacktoberfest 2025 - Testing*

No files, functions, or existing test entry points are named. Start by locating the repository's core Python functions and checking whether pytest is already configured; then verify the 70% coverage target and that GitHub Actions runs tests on each commit. Document the resulting testing procedure.

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