Phase 5: Add comprehensive Google-style doctests to all transport modules, ensure flake8 and pre-commit compliance (#450)

Author: manavgup

mcpgateway/transports/__init__.py

@@ -9,6 +9,45 @@
 - stdio: Communication over standard input/output
 - SSE: Server-Sent Events for server-to-client streaming
 - WebSocket: Full-duplex communication
+
+Examples:
+    >>> # Import all available transport classes
+    >>> from mcpgateway.transports import Transport, StdioTransport, SSETransport, WebSocketTransport
+    >>>
+    >>> # Verify all classes are imported correctly
+    >>> Transport.__name__
+    'Transport'
+    >>> StdioTransport.__name__
+    'StdioTransport'
+    >>> SSETransport.__name__
+    'SSETransport'
+    >>> WebSocketTransport.__name__
+    'WebSocketTransport'
+
+    >>> # Check that all transports inherit from base Transport
+    >>> from mcpgateway.transports.base import Transport
+    >>> issubclass(StdioTransport, Transport)
+    True
+    >>> issubclass(SSETransport, Transport)
+    True
+    >>> issubclass(WebSocketTransport, Transport)
+    True
+
+    >>> # Verify __all__ exports all expected classes
+    >>> from mcpgateway.transports import __all__
+    >>> sorted(__all__)
+    ['SSETransport', 'StdioTransport', 'Transport', 'WebSocketTransport']
+
+    >>> # Test that we can instantiate transport classes
+    >>> stdio = StdioTransport()
+    >>> isinstance(stdio, Transport)
+    True
+    >>> sse = SSETransport("http://localhost:8000")
+    >>> isinstance(sse, Transport)
+    True
+    >>> ws = WebSocketTransport("ws://localhost:8000")
+    >>> isinstance(ws, Transport)
+    True
 """
 
 from mcpgateway.transports.base import Transport

mcpgateway/transports/base.py

@@ -14,22 +14,84 @@
 
 
 class Transport(ABC):
-    """Base class for MCP transport implementations."""
+    """Base class for MCP transport implementations.
+
+    This abstract base class defines the interface that all MCP transport
+    implementations must follow. It provides the core methods for connection
+    management and message exchange.
+
+    Examples:
+        >>> # Transport is abstract and cannot be instantiated directly
+        >>> try:
+        ...     Transport()
+        ... except TypeError as e:
+        ...     print("Cannot instantiate abstract class")
+        Cannot instantiate abstract class
+
+        >>> # Check if Transport is an abstract base class
+        >>> from abc import ABC
+        >>> issubclass(Transport, ABC)
+        True
+
+        >>> # Verify abstract methods are defined
+        >>> hasattr(Transport, 'connect')
+        True
+        >>> hasattr(Transport, 'disconnect')
+        True
+        >>> hasattr(Transport, 'send_message')
+        True
+        >>> hasattr(Transport, 'receive_message')
+        True
+        >>> hasattr(Transport, 'is_connected')
+        True
+    """
 
     @abstractmethod
     async def connect(self) -> None:
-        """Initialize transport connection."""
+        """Initialize transport connection.
+
+        This method should establish the underlying connection for the transport.
+        It must be called before sending or receiving messages.
+
+        Examples:
+            >>> # This is an abstract method - implementation required in subclasses
+            >>> import inspect
+            >>> inspect.ismethod(Transport.connect)
+            False
+            >>> hasattr(Transport, 'connect')
+            True
+        """
 
     @abstractmethod
     async def disconnect(self) -> None:
-        """Close transport connection."""
+        """Close transport connection.
+
+        This method should clean up the underlying connection and any associated
+        resources. It should be called when the transport is no longer needed.
+
+        Examples:
+            >>> # This is an abstract method - implementation required in subclasses
+            >>> import inspect
+            >>> inspect.ismethod(Transport.disconnect)
+            False
+            >>> hasattr(Transport, 'disconnect')
+            True
+        """
 
     @abstractmethod
     async def send_message(self, message: Dict[str, Any]) -> None:
         """Send a message over the transport.
 
         Args:
             message: Message to send
+
+        Examples:
+            >>> # This is an abstract method - implementation required in subclasses
+            >>> import inspect
+            >>> inspect.ismethod(Transport.send_message)
+            False
+            >>> hasattr(Transport, 'send_message')
+            True
         """
 
     @abstractmethod
@@ -38,6 +100,14 @@ async def receive_message(self) -> AsyncGenerator[Dict[str, Any], None]:
 
         Yields:
             Received messages
+
+        Examples:
+            >>> # This is an abstract method - implementation required in subclasses
+            >>> import inspect
+            >>> inspect.ismethod(Transport.receive_message)
+            False
+            >>> hasattr(Transport, 'receive_message')
+            True
         """
 
     @abstractmethod
@@ -46,4 +116,12 @@ async def is_connected(self) -> bool:
 
         Returns:
             True if connected
+
+        Examples:
+            >>> # This is an abstract method - implementation required in subclasses
+            >>> import inspect
+            >>> inspect.ismethod(Transport.is_connected)
+            False
+            >>> hasattr(Transport, 'is_connected')
+            True
         """