chore: add D212 lint rule to enforce Google-style docstrings (#1892)

tests/issues/test_1027_win_unreachable_cleanup.py

@@ -1,5 +1,4 @@
-"""
-Regression test for issue #1027: Ensure cleanup procedures run properly during shutdown
+"""Regression test for issue #1027: Ensure cleanup procedures run properly during shutdown
 
 Issue #1027 reported that cleanup code after "yield" in lifespan was unreachable when
 processes were terminated. This has been fixed by implementing the MCP spec-compliant
@@ -23,8 +22,7 @@ from tests.shared.test_win32_utils import escape_path_for_python
 
 @pytest.mark.anyio
 async def test_lifespan_cleanup_executed():
-    """
-    Regression test ensuring MCP server cleanup code runs during shutdown.
+    """Regression test ensuring MCP server cleanup code runs during shutdown.
 
     This test verifies that the fix for issue #1027 works correctly by:
     1. Starting an MCP server that writes a marker file on startup
@@ -124,8 +122,7 @@ async def test_lifespan_cleanup_executed():
 @pytest.mark.anyio
 @pytest.mark.filterwarnings("ignore::ResourceWarning" if sys.platform == "win32" else "default")
 async def test_stdin_close_triggers_cleanup():
-    """
-    Regression test verifying the stdin-based graceful shutdown mechanism.
+    """Regression test verifying the stdin-based graceful shutdown mechanism.
 
     This test ensures the core fix for issue #1027 continues to work by:
     1. Manually managing a server process

tests/issues/test_1363_race_condition_streamable_http.py

@@ -90,8 +90,7 @@ class ServerThread(threading.Thread):
 
 
 def check_logs_for_race_condition_errors(caplog: pytest.LogCaptureFixture, test_name: str) -> None:
-    """
-    Check logs for ClosedResourceError and other race condition errors.
+    """Check logs for ClosedResourceError and other race condition errors.
 
     Args:
         caplog: pytest log capture fixture
@@ -121,8 +120,7 @@ def check_logs_for_race_condition_errors(caplog: pytest.LogCaptureFixture, test_
 
 @pytest.mark.anyio
 async def test_race_condition_invalid_accept_headers(caplog: pytest.LogCaptureFixture):
-    """
-    Test the race condition with invalid Accept headers.
+    """Test the race condition with invalid Accept headers.
 
     This test reproduces the exact scenario described in issue #1363:
     - Send POST request with incorrect Accept headers (missing either application/json or text/event-stream)
@@ -196,8 +194,7 @@ async def test_race_condition_invalid_accept_headers(caplog: pytest.LogCaptureFi
 
 @pytest.mark.anyio
 async def test_race_condition_invalid_content_type(caplog: pytest.LogCaptureFixture):
-    """
-    Test the race condition with invalid Content-Type headers.
+    """Test the race condition with invalid Content-Type headers.
 
     This test reproduces the race condition scenario with Content-Type validation failure.
     """
@@ -237,8 +234,7 @@ async def test_race_condition_invalid_content_type(caplog: pytest.LogCaptureFixt
 
 @pytest.mark.anyio
 async def test_race_condition_message_router_async_for(caplog: pytest.LogCaptureFixture):
-    """
-    Uses json_response=True to trigger the `if self.is_json_response_enabled` branch,
+    """Uses json_response=True to trigger the `if self.is_json_response_enabled` branch,
     which reproduces the ClosedResourceError when message_router is suspended
     in async for loop while transport cleanup closes streams concurrently.
     """

tests/issues/test_552_windows_hang.py

@@ -13,8 +13,7 @@ from mcp.client.stdio import stdio_client
 @pytest.mark.skipif(sys.platform != "win32", reason="Windows-specific test")  # pragma: no cover
 @pytest.mark.anyio
 async def test_windows_stdio_client_with_session():
-    """
-    Test the exact scenario from issue #552: Using ClientSession with stdio_client.
+    """Test the exact scenario from issue #552: Using ClientSession with stdio_client.
 
     This reproduces the original bug report where stdio_client hangs on Windows 11
     when used with ClientSession.

tests/issues/test_malformed_input.py

@@ -20,8 +20,7 @@ from mcp.types import (
 
 @pytest.mark.anyio
 async def test_malformed_initialize_request_does_not_crash_server():
-    """
-    Test that malformed initialize requests return proper error responses
+    """Test that malformed initialize requests return proper error responses
     instead of crashing the server (HackerOne #3156202).
     """
     # Create in-memory streams for testing
@@ -101,9 +100,7 @@ async def test_malformed_initialize_request_does_not_crash_server():
 
 @pytest.mark.anyio
 async def test_multiple_concurrent_malformed_requests():
-    """
-    Test that multiple concurrent malformed requests don't crash the server.
-    """
+    """Test that multiple concurrent malformed requests don't crash the server."""
     # Create in-memory streams for testing
     read_send_stream, read_receive_stream = anyio.create_memory_object_stream[SessionMessage | Exception](100)
     write_send_stream, write_receive_stream = anyio.create_memory_object_stream[SessionMessage](100)