Add comprehensive unit tests for PhpSIP class

[devin-ai-integration]

Add comprehensive unit tests for PhpSIP class

Summary

This PR adds comprehensive unit tests for the PhpSIP class to ensure proper functionality and validate the PHP 8.4 compatibility changes made in the previous refactoring work. The tests focus on validating class structure, method existence, and parameter type compatibility without requiring actual network operations.

Key additions:

• PhpSIPTest.php - 6 comprehensive tests covering PHP 8.4 nullable parameter compatibility, class structure validation, and method existence
• PhpSIPExceptionTest.php - 4 tests for the exception class functionality
• phpunit.xml - PHPUnit configuration with coverage reporting
• composer.json - Package management setup with PHPUnit dependencies

Test approach: Due to the PhpSIP class's heavy dependence on socket operations, the tests are designed to validate class structure and PHP 8.4 compatibility without requiring actual network connectivity. Tests use reflection to validate parameter types and method signatures.

Review & Testing Checklist for Human

• Run the test suite locally - Verify all tests pass with vendor/bin/phpunit and that the PHP 8.4 compatibility changes work correctly
• Review test methodology - Confirm the reflection-based testing approach is appropriate given the network dependency constraints
• Validate PHP 8.4 compatibility - Ensure the nullable parameter type declarations are working as expected in the constructor and setter methods
• Consider integration testing needs - Assess whether additional functional tests with actual SIP operations are needed for production confidence

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    subgraph "Test Files"
        PhpSIPTest["tests/PhpSIPTest.php<br/>Unit Tests"]:::major-edit
        PhpSIPExceptionTest["tests/PhpSIPExceptionTest.php<br/>Exception Tests"]:::major-edit
    end
    
    subgraph "Configuration"
        composer["composer.json<br/>Dependencies"]:::major-edit
        phpunit["phpunit.xml<br/>Test Config"]:::major-edit
    end
    
    subgraph "Source Code"
        PhpSIP["PhpSIP.class.php<br/>Main Class"]:::context
        PhpSIPException["PhpSIP.Exception.php<br/>Exception Class"]:::context
    end
    
    PhpSIPTest --> PhpSIP
    PhpSIPExceptionTest --> PhpSIPException
    composer --> PhpSIPTest
    phpunit --> PhpSIPTest
    phpunit --> PhpSIPExceptionTest
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit  
        L3[Context/No Edit]:::context
    end

    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Testing constraints: The PhpSIP class constructor fails in test environments due to socket creation requirements, so tests focus on structural validation rather than functional testing
• PHP 8.4 compatibility: Tests specifically validate that the nullable parameter type declarations added in the previous refactoring work correctly
• Coverage limitations: While comprehensive for class structure, the tests don't cover actual SIP protocol operations, authentication logic, or socket communications due to network dependencies
• Session details: Requested by @l7s - Link to Devin run: https://app.devin.ai/sessions/765f7395244241abbbdf2dc2516f7015

[devin-ai-integration]

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