Add is_disconnected property to WebSocket

starlette/websockets.py

@@ -32,6 +32,13 @@ def __init__(self, scope: Scope, receive: Receive, send: Send) -> None:
         self.client_state = WebSocketState.CONNECTING
         self.application_state = WebSocketState.CONNECTING
 
+    @property
+    def is_disconnected(self) -> bool:
+        return (
+            self.client_state == WebSocketState.DISCONNECTED
+            or self.application_state == WebSocketState.DISCONNECTED
+        )
+
     async def receive(self) -> Message:
         """
         Receive ASGI websocket messages, ensuring valid state transitions.

tests/test_websockets.py

@@ -651,3 +651,18 @@ async def app(scope: Scope, receive: Receive, send: Send) -> None:
     with pytest.raises(RuntimeError):
         with client.websocket_connect("/") as websocket:
             websocket.send({"type": "websocket.connect"})
+
+
+def test_is_disconnected_property(test_client_factory: TestClientFactory) -> None:
+    async def app(scope: Scope, receive: Receive, send: Send) -> None:
+        websocket = WebSocket(scope, receive=receive, send=send)
+        assert not websocket.is_disconnected
+        await websocket.accept()
+        assert not websocket.is_disconnected
+        message = await websocket.receive()
+        websocket.client_state = WebSocketState.DISCONNECTED
+        assert websocket.is_disconnected
+
+    client = test_client_factory(app)
+    with client.websocket_connect("/") as websocket:
+        websocket.send_json({"close": True})