Convert unittest test cases to pytest

[DhavalGojiya]

Convert unittest test cases to pytest

PyTest --> https://docs.pytest.org/en/stable/

Summary

This project test files still use Python's built in unittest framework. Converting them to pytest will make the test suite more consistent, easier to read, and simpler to maintain.

Tasks

• Convert existing unittest.TestCase classes to pytest style tests.
• Replace self.assert* methods with standard assert statements.
• Use pytest fixtures where appropriate instead of setUp and tearDown.
• Ensure all existing test coverage is preserved.
• Verify the full test suite passes after the migration.