Use spawn instead of fork to prevent sniffio detecting the wrong async library on the test server

Author: agronholm

tests/server/test_sse_security.py

@@ -68,7 +68,8 @@ async def handle_sse(request: Request):
 
 def start_server_process(port: int, security_settings: TransportSecuritySettings | None = None):
     """Start server in a separate process."""
-    process = multiprocessing.Process(target=run_server_with_settings, args=(port, security_settings))
+    context = multiprocessing.get_context("spawn")
+    process = context.Process(target=run_server_with_settings, args=(port, security_settings))
     process.start()
     # Give server time to start
     time.sleep(1)

tests/server/test_streamable_http_security.py

@@ -75,7 +75,8 @@ async def lifespan(app: Starlette) -> AsyncGenerator[None, None]:
 
 def start_server_process(port: int, security_settings: TransportSecuritySettings | None = None):
     """Start server in a separate process."""
-    process = multiprocessing.Process(target=run_server_with_settings, args=(port, security_settings))
+    context = multiprocessing.get_context("spawn")
+    process = context.Process(target=run_server_with_settings, args=(port, security_settings))
     process.start()
     # Give server time to start
     time.sleep(1)