[DOCS] Create comprehensive documentation for test infrastructure and testing guidelines

[najeed]

Documentation Type

• API documentation
• Tutorial/Guide
• Code comments

Current Problem
New test files have been added to the project, but there's no comprehensive documentation covering:

• Test architecture and organization
• How to run different test suites
• Guidelines for writing new tests
• Test coverage expectations
• Integration testing patterns

Proposed Solution
Create comprehensive testing documentation that covers:

1. Test Architecture Guide

   • Test directory structure explanation
   • Unit vs integration vs end-to-end test organization
   • Test naming conventions and patterns
   • Mock and fixture usage guidelines

2. Developer Testing Guide

   • How to run all tests: pytest
   • How to run specific test categories
   • Coverage reporting and requirements
   • Performance testing procedures

3. Test Writing Guidelines

   • Template for new test files
   • Best practices for agent testing
   • Scenario validation testing patterns
   • Error condition testing requirements

Target Audience

• New contributors
• Developers integrating the library
• Contributors adding new features

Files to Create/Update

• docs/guides/testing/overview.md
• docs/guides/testing/running-tests.md
• docs/guides/testing/writing-tests.md
• docs/guides/testing/test-patterns.md
• TESTING.md (root level quick reference)

Content Structure

# Testing Documentation Structure

## /docs/guides/testing/overview.md
- Test architecture explanation
- Directory structure guide
- Test categories and purposes

## /docs/guides/testing/running-tests.md
- Installation of test dependencies
- Running full test suite
- Running specific test categories
- Coverage reporting
- Performance benchmarking

## /docs/guides/testing/writing-tests.md
- Test file templates
- Naming conventions
- Mock usage patterns
- Agent testing best practices
- Scenario validation testing

## /docs/guides/testing/test-patterns.md
- Common testing patterns for evaluation frameworks
- Error condition testing
- Performance testing guidelines
- Integration testing strategies

Acceptance Criteria

• Complete overview of test infrastructure
• Step-by-step guide for running tests
• Templates and examples for writing new tests
• Clear guidelines for test coverage expectations
• Integration with main documentation navigation

Learning Opportunities
Contributors will understand the testing philosophy and be able to confidently add tests for new features.

Estimated Time

• 1-2 days

Additional Context
Essential for maintaining code quality as more contributors join the project. Good testing documentation reduces barrier to entry for new contributors.