[TASK] Add Unit, Integration, and E2E Tests for Socketmap Enhancements

[Aravinda-HWK]

What needs to be done?

Description:

With the recent improvements and refactoring around the socketmap service (including shared logic, caching, and group member validation), we need to introduce proper test coverage to ensure reliability and prevent regressions.

Scope:

Implement comprehensive testing across different levels:

Tasks:

1. Unit Tests

   - Cover core functions such as caching logic and shared utilities.
   - Ensure edge cases and error scenarios are handled correctly.
   

2. Integration Tests

   - Test interactions between socketmap, LMTP, and authentication components.
   - Validate correct behavior of shared cache and reused logic.
   

3. End-to-End (E2E) Tests

    - Simulate real mail flow scenarios.
    - Verify group email handling and member validation from end to end.
   

Goal:

• Ensure stability after refactoring
• Improve confidence in future changes
• Detect regressions early in the development cycle

Additional Notes:

• Integrate tests into CI/CD pipeline
• Maintain clear structure for test organization (unit/integration/e2e separation)