remove monkeypatching TestClient interface

starlette/testclient.py

@@ -91,11 +91,16 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
         await instance(receive, send)
 
 
+class _AsyncBackend(typing.TypedDict):
+    backend: str
+    backend_options: typing.Dict[str, typing.Any]
+
+
 class _ASGIAdapter(requests.adapters.HTTPAdapter):
     def __init__(
         self,
         app: ASGI3App,
-        async_backend: typing.Dict[str, typing.Any],
+        async_backend: _AsyncBackend,
         raise_server_exceptions: bool = True,
         root_path: str = "",
     ) -> None:
@@ -271,7 +276,10 @@ async def send(message: Message) -> None:
 
 class WebSocketTestSession:
     def __init__(
-        self, app: ASGI3App, scope: Scope, async_backend: typing.Dict[str, typing.Any]
+        self,
+        app: ASGI3App,
+        scope: Scope,
+        async_backend: _AsyncBackend,
     ) -> None:
         self.app = app
         self.scope = scope
@@ -381,11 +389,6 @@ def receive_json(self, mode: str = "text") -> typing.Any:
 
 class TestClient(requests.Session):
     __test__ = False  # For pytest to not discover this up.
-    #: These are the default options for the constructor arguments
-    async_backend: typing.Dict[str, typing.Any] = {
-        "backend": "asyncio",
-        "backend_options": {},
-    }
     task: "Future[None]"
 
     def __init__(
@@ -394,14 +397,13 @@ def __init__(
         base_url: str = "http://testserver",
         raise_server_exceptions: bool = True,
         root_path: str = "",
-        backend: typing.Optional[str] = None,
+        backend: str = "asyncio",
         backend_options: typing.Optional[typing.Dict[str, typing.Any]] = None,
     ) -> None:
         super().__init__()
-        self.async_backend = {
-            "backend": backend or self.async_backend["backend"],
-            "backend_options": backend_options or self.async_backend["backend_options"],
-        }
+        self.async_backend = _AsyncBackend(
+            backend=backend, backend_options=backend_options or {}
+        )
         if _is_asgi3(app):
             app = typing.cast(ASGI3App, app)
             asgi_app = app