enhanced-mcp-tools/docs/TESTING_STRATEGY.md

Enhanced MCP Tools Testing Strategy

This document outlines our comprehensive testing approach that combines multiple testing methodologies to ensure reliability, safety, and compliance with FastMCP best practices.

Testing Architecture Overview

We implement a multi-layered testing strategy that provides different levels of validation:

┌─────────────────────────────────────────────────────────┐
│                 Transport-Level Testing                 │
│  (FastMCP Recommended: Process-based integration)      │
├─────────────────────────────────────────────────────────┤
│                Integration Testing                      │
│     (Tool registration, server composition)            │
├─────────────────────────────────────────────────────────┤
│                  Unit Testing                           │
│        (Individual tool functionality)                 │
└─────────────────────────────────────────────────────────┘

1. Transport-Level Testing (FastMCP Recommended)

File: tests/test_fastmcp_recommended.py Purpose: Tests the full server startup and process lifecycle following FastMCP guidelines.

What It Tests

• ✅ Server Process Startup: Verifies server can start in stdio mode (default MCP transport)
• ✅ Tool Discovery: Uses CLI --list-tools to verify tool registration
• ✅ Process Management: Tests graceful startup and shutdown
• ✅ Real Environment: Tests in actual subprocess environment

Key Features

class MCPServerProcess:
    """Context manager for running MCP server in subprocess"""
    # Starts actual server process
    # Waits for initialization
    # Handles graceful cleanup

Benefits

• Closest to Production: Tests how the server actually runs
• Real Process Testing: Catches issues that unit tests miss
• Transport Validation: Verifies stdio/HTTP transport modes work
• CLI Interface Testing: Validates --list-tools and other CLI features

2. Integration Testing

File: tests/test_mcp_integration.py Purpose: Tests server composition, tool registration, and module interactions.

What It Tests

• ✅ Server Creation: Verifies create_server() function works
• ✅ Tool Registration: Confirms all 50+ tools register correctly
• ✅ Prefix Management: Ensures no naming conflicts
• ✅ MCPMixin Compliance: Validates proper inheritance patterns
• ✅ Tool Execution: Tests tools can be called through server
• ✅ Error Handling: Verifies graceful error responses

Key Features

def test_server_creation():
    """Test FastMCP server creation with all modules"""
    server = create_server()
    assert server is not None

async def test_tool_registration_count():
    """Verify all expected tools are registered"""
    tools = await server.get_tools()
    assert len(tools) >= 50  # Minimum expected tools

Benefits

• Module Interaction: Tests how different tool modules work together
• Registration Validation: Ensures all tools are properly registered
• FastMCP Compliance: Verifies server follows FastMCP patterns
• Tool Discovery: Tests async get_tools() functionality

3. Unit Testing

File: tests/test_screenshot_tools.py (example) Purpose: Tests individual tool functionality in isolation.

What It Tests

• ✅ Tool Logic: Individual function behavior
• ✅ Parameter Validation: Input validation and error handling
• ✅ Mock Integration: Tests with mocked dependencies
• ✅ Edge Cases: Boundary conditions and error scenarios
• ✅ Performance: Concurrent execution and resource usage

Key Features

class TestScreenshotToolsUnit:
    def test_take_screenshot_with_mock_display(self):
        """Test screenshot with mocked PIL"""
        # Uses unittest.mock to test without real display

class TestScreenshotToolsErrorHandling:
    def test_exception_handling(self):
        """Test graceful error handling"""
        # Verifies tools fail gracefully

Benefits

• Fast Execution: Rapid feedback during development
• Isolated Testing: Tests individual components without dependencies
• Mock Support: Can test without external resources (display, network)
• Comprehensive Coverage: Tests all code paths and edge cases

Current Test Results

Test Coverage Summary

Transport-Level:    3 passed, 3 skipped  (1.0s execution)
Integration:       15 passed              (0.5s execution)
Unit Tests:        22 passed              (0.4s execution)
─────────────────────────────────────────────────────────
Total:             40 passed, 3 skipped  (1.9s total)

Testing Performance

• Unit Tests: ~0.4s (immediate feedback)
• Integration: ~0.5s (module validation)
• Transport: ~1.0s (full server lifecycle)
• Total Suite: <2s (excellent for CI/CD)

When to Use Each Level

🔄 Development Workflow

1. Unit Tests: Run continuously during development

   PYTHONPATH=src uv run pytest tests/test_screenshot_tools.py -v
   

2. Integration Tests: Run before committing changes

   PYTHONPATH=src uv run pytest tests/test_mcp_integration.py -v
   

3. Transport Tests: Run before releases/deployment

   PYTHONPATH=src uv run pytest tests/test_fastmcp_recommended.py -v
   

🚀 CI/CD Pipeline

# Full test suite
PYTHONPATH=src uv run pytest tests/ -v

FastMCP Compliance Analysis

✅ What We Follow

• MCPMixin Pattern: All tools inherit from MCPMixin
• Async Tools: All @mcp_tool functions are async
• Tool Registration: Use register_all() with prefixes
• Server Composition: Create FastMCP app and register modules
• Transport Testing: Test actual server process startup

⚠️ Limitations (Due to Dependencies)

• Full MCP Client: Would require mcp client library for JSON-RPC testing
• run_server_in_process: Not available in current FastMCP version
• Network Transport: Would need MCP client to test HTTP/WebSocket transports

🔮 Future Enhancements

When FastMCP testing dependencies become available:

# Future enhancement example
from fastmcp.testing import run_server_in_process
from mcp import Client

async def test_full_mcp_protocol():
    with run_server_in_process(create_server) as url:
        async with Client(transport=HttpTransport(url)) as client:
            result = await client.call_tool("automation_take_screenshot", {})
            assert result is not None

Safety Testing Integration

Our tests also validate the SACRED TRUST safety framework:

• Dry Run Validation: Tests verify destructive tools default to dry_run=True
• Security Level Testing: Validates tool categorization (SAFE/CAUTION/DESTRUCTIVE)
• Progressive Disclosure: Tests that dangerous tools are hidden by default
• Error Handling: Ensures tools fail gracefully rather than causing damage

Best Practices Demonstrated

🛡️ Safety First

• Mock External Resources: Don't depend on real displays, networks, filesystems
• Isolated Testing: Each test is independent
• Graceful Degradation: Tests work even in headless environments

⚡ Performance Optimized

• Fast Feedback: Unit tests provide immediate results
• Parallel Execution: pytest-asyncio handles concurrent tests
• Resource Efficient: Minimal memory and CPU usage

🔧 Maintainable

• Clear Structure: Separate unit, integration, and transport concerns
• Comprehensive Coverage: Multiple validation levels catch different issues
• Documentation: Each test explains its purpose and validation scope

Running the Complete Test Suite

# Install test dependencies
uv sync --extra dev

# Run all tests with coverage
PYTHONPATH=src uv run pytest --cov=enhanced_mcp --cov-report=html tests/

# Run specific test levels
PYTHONPATH=src uv run pytest tests/test_screenshot_tools.py -v      # Unit
PYTHONPATH=src uv run pytest tests/test_mcp_integration.py -v       # Integration
PYTHONPATH=src uv run pytest tests/test_fastmcp_recommended.py -v   # Transport

This multi-layered approach ensures Enhanced MCP Tools meets enterprise-grade reliability standards while following FastMCP best practices and maintaining rapid development velocity.