"""
Debugpy Server Fixture
This module provides a proper debugpy server implementation for testing the MCP server.
It demonstrates the correct pattern where:
1. This script starts debugpy in listening mode
2. The MCP server connects to this debugpy instance as a DAP client
"""
import sys
import os
import time
import argparse
try:
import debugpy
print(f"Debugpy imported successfully (version: {debugpy.__version__})")
except ImportError as e:
print(f"Failed to import debugpy: {e}")
sys.exit(1)
# Default configuration
DEFAULT_HOST = "127.0.0.1"
DEFAULT_PORT = 5679 # Using a different port to avoid conflicts
def start_debugpy_server(host=DEFAULT_HOST, port=DEFAULT_PORT, wait_for_client=True):
"""
Start a debugpy server in listening mode
Args:
host: Host to listen on
port: Port to listen on
wait_for_client: Whether to wait for a client to connect
Returns:
True if server started successfully, False otherwise
"""
print(f"Starting debugpy server at {host}:{port}")
try:
# Start the debugpy server - this is the correct usage pattern
debugpy.listen((host, port))
print("Debugpy server is listening!")
# Enable wait_for_client to pause until the MCP server connects
if wait_for_client:
print("Waiting for client to connect...")
debugpy.wait_for_client()
print("Client connected to debugpy server!")
return True
except Exception as e:
print(f"Error starting debugpy server: {e}")
return False
def fibonacci(n):
"""A simple Fibonacci function for debugging"""
print(f"Calculating Fibonacci for n={n}")
if n <= 0:
return 0
elif n == 1:
return 1
a, b = 0, 1
for _ in range(1, n):
a, b = b, a + b
result = b
print(f"Fibonacci({n}) = {result}")
return result
def run_fibonacci_test():
"""Run a simple fibonacci test with a breakpoint"""
# Set a breakpoint programmatically
debugpy.breakpoint()
print("Hit breakpoint")
# Run some simple code that can be debugged
fibonacci(10)
print("Script execution completed")
return True
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Debugpy server for testing")
parser.add_argument("--host", default=DEFAULT_HOST, help="Host to listen on")
parser.add_argument("--port", type=int, default=DEFAULT_PORT, help="Port to listen on")
parser.add_argument("--no-wait", action="store_true", help="Don't wait for client connection")
parser.add_argument("--run-test", action="store_true", help="Run the fibonacci test")
args = parser.parse_args()
success = start_debugpy_server(args.host, args.port, not args.no_wait)
if not success:
sys.exit(1)
if args.run_test:
run_fibonacci_test()
else:
# Keep the script running indefinitely
print("Running in server mode. Press Ctrl+C to exit...")
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
print("Server stopped.")
# Keep the script running for a bit to allow time for debugging
print("Waiting before exit...")
time.sleep(5)
print("Exiting")
