Improve Test Coverage and Add Missing Test Cases

Description

Some core modules lacked sufficient test coverage, making it difficult to ensure reliability and catch regressions during development. Existing tests did not fully cover edge cases, error handling, and critical logic paths.

Changes Made

Added new test cases for uncovered and partially covered files
Improved overall test coverage across key modules
Included edge case scenarios and error handling validations
Refactored some existing tests for better clarity and maintainability

Why This is Needed

Ensures stability of core functionalities
Reduces risk of bugs during future changes
Improves confidence in CI/CD pipelines
Helps maintain code quality standards

Expected Outcome

Increased test coverage percentage
More robust and reliable test suite
Better detection of edge case failures

How to Verify

Run tests:
```
npm run test
```
Check coverage:
```
npm run test:coverage
```
Confirm improved coverage metrics and all tests passing