Add unit tests for existing Python modules

[techupskills]

There are several Python files in the repository that lack comprehensive unit tests. To improve code reliability and maintainability, add unit tests for all core modules and functions.

Tasks:

• Identify Python files missing tests.
• Create or expand test cases for important functions and classes.
• Ensure tests cover edge cases and expected failures.
• Integrate new tests into the CI workflow.

Acceptance Criteria:

• All major Python modules have tests with at least 80% code coverage.
• Tests run successfully in the CI pipeline.