diff --git a/tests/conftest.py b/tests/conftest.py
index 724ca65d3..21f56a054 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,13 +1,12 @@
 from __future__ import annotations
 
 import functools
-from typing import Any, Callable, Literal
+from typing import Any, Literal
 
 import pytest
 
 from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 @pytest.fixture
@@ -21,4 +20,4 @@ def test_client_factory(
         TestClient,
         backend=anyio_backend_name,
         backend_options=anyio_backend_options,
-    )
+    )  # type: ignore
diff --git a/tests/middleware/test_base.py b/tests/middleware/test_base.py
index 2176404d8..3ad1751a2 100644
--- a/tests/middleware/test_base.py
+++ b/tests/middleware/test_base.py
@@ -5,7 +5,6 @@
 from typing import (
     Any,
     AsyncGenerator,
-    Callable,
     Generator,
 )
 
@@ -23,8 +22,7 @@
 from starlette.testclient import TestClient
 from starlette.types import ASGIApp, Message, Receive, Scope, Send
 from starlette.websockets import WebSocket
-
-TestClientFactory = Callable[[ASGIApp], TestClient]
+from tests.types import TestClientFactory
 
 
 class CustomMiddleware(BaseHTTPMiddleware):
diff --git a/tests/middleware/test_cors.py b/tests/middleware/test_cors.py
index 09ec9513f..630361243 100644
--- a/tests/middleware/test_cors.py
+++ b/tests/middleware/test_cors.py
@@ -1,15 +1,10 @@
-from typing import Callable
-
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
 from starlette.middleware.cors import CORSMiddleware
 from starlette.requests import Request
 from starlette.responses import PlainTextResponse
 from starlette.routing import Route
-from starlette.testclient import TestClient
-from starlette.types import ASGIApp
-
-TestClientFactory = Callable[[ASGIApp], TestClient]
+from tests.types import TestClientFactory
 
 
 def test_cors_allow_all(
diff --git a/tests/middleware/test_errors.py b/tests/middleware/test_errors.py
index a2dbabd8a..e32f406ae 100644
--- a/tests/middleware/test_errors.py
+++ b/tests/middleware/test_errors.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable
+from typing import Any
 
 import pytest
 
@@ -8,10 +8,8 @@
 from starlette.requests import Request
 from starlette.responses import JSONResponse, Response
 from starlette.routing import Route
-from starlette.testclient import TestClient
 from starlette.types import Receive, Scope, Send
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_handler(
diff --git a/tests/middleware/test_gzip.py b/tests/middleware/test_gzip.py
index 5bfecadb7..ea9489452 100644
--- a/tests/middleware/test_gzip.py
+++ b/tests/middleware/test_gzip.py
@@ -1,15 +1,10 @@
-from typing import Callable
-
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
 from starlette.middleware.gzip import GZipMiddleware
 from starlette.requests import Request
 from starlette.responses import ContentStream, PlainTextResponse, StreamingResponse
 from starlette.routing import Route
-from starlette.testclient import TestClient
-from starlette.types import ASGIApp
-
-TestClientFactory = Callable[[ASGIApp], TestClient]
+from tests.types import TestClientFactory
 
 
 def test_gzip_responses(test_client_factory: TestClientFactory) -> None:
@@ -29,7 +24,9 @@ def homepage(request: Request) -> PlainTextResponse:
     assert int(response.headers["Content-Length"]) < 4000
 
 
-def test_gzip_not_in_accept_encoding(test_client_factory: TestClientFactory) -> None:
+def test_gzip_not_in_accept_encoding(
+    test_client_factory: TestClientFactory,
+) -> None:
     def homepage(request: Request) -> PlainTextResponse:
         return PlainTextResponse("x" * 4000, status_code=200)
 
diff --git a/tests/middleware/test_https_redirect.py b/tests/middleware/test_https_redirect.py
index 9195694a3..22dfc14b6 100644
--- a/tests/middleware/test_https_redirect.py
+++ b/tests/middleware/test_https_redirect.py
@@ -1,14 +1,10 @@
-from typing import Callable
-
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
 from starlette.middleware.httpsredirect import HTTPSRedirectMiddleware
 from starlette.requests import Request
 from starlette.responses import PlainTextResponse
 from starlette.routing import Route
-from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_https_redirect_middleware(test_client_factory: TestClientFactory) -> None:
diff --git a/tests/middleware/test_session.py b/tests/middleware/test_session.py
index 4fbeec88c..9a0d70a0d 100644
--- a/tests/middleware/test_session.py
+++ b/tests/middleware/test_session.py
@@ -1,5 +1,4 @@
 import re
-from typing import Callable
 
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
@@ -8,8 +7,7 @@
 from starlette.responses import JSONResponse
 from starlette.routing import Mount, Route
 from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def view_session(request: Request) -> JSONResponse:
diff --git a/tests/middleware/test_trusted_host.py b/tests/middleware/test_trusted_host.py
index 466302210..ddff46c48 100644
--- a/tests/middleware/test_trusted_host.py
+++ b/tests/middleware/test_trusted_host.py
@@ -1,14 +1,10 @@
-from typing import Callable
-
 from starlette.applications import Starlette
 from starlette.middleware import Middleware
 from starlette.middleware.trustedhost import TrustedHostMiddleware
 from starlette.requests import Request
 from starlette.responses import PlainTextResponse
 from starlette.routing import Route
-from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_trusted_host_middleware(test_client_factory: TestClientFactory) -> None:
diff --git a/tests/middleware/test_wsgi.py b/tests/middleware/test_wsgi.py
index 69842d3ad..58696bb65 100644
--- a/tests/middleware/test_wsgi.py
+++ b/tests/middleware/test_wsgi.py
@@ -5,10 +5,9 @@
 
 from starlette._utils import collapse_excgroups
 from starlette.middleware.wsgi import WSGIMiddleware, build_environ
-from starlette.testclient import TestClient
+from tests.types import TestClientFactory
 
 WSGIResponse = Iterable[bytes]
-TestClientFactory = Callable[..., TestClient]
 StartResponse = Callable[..., Any]
 Environment = Dict[str, Any]
 
diff --git a/tests/test_applications.py b/tests/test_applications.py
index 5b6c9d545..1a7228a33 100644
--- a/tests/test_applications.py
+++ b/tests/test_applications.py
@@ -1,7 +1,7 @@
 import os
 from contextlib import asynccontextmanager
 from pathlib import Path
-from typing import AsyncGenerator, AsyncIterator, Callable, Generator
+from typing import AsyncGenerator, AsyncIterator, Generator
 
 import anyio
 import pytest
@@ -20,8 +20,7 @@
 from starlette.testclient import TestClient
 from starlette.types import ASGIApp, Receive, Scope, Send
 from starlette.websockets import WebSocket
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 async def error_500(request: Request, exc: HTTPException) -> JSONResponse:
@@ -132,7 +131,9 @@ def custom_ws_exception_handler(websocket: WebSocket, exc: CustomWSException) ->
 
 
 @pytest.fixture
-def client(test_client_factory: TestClientFactory) -> Generator[TestClient, None, None]:
+def client(
+    test_client_factory: TestClientFactory,
+) -> Generator[TestClient, None, None]:
     with test_client_factory(app) as client:
         yield client
 
diff --git a/tests/test_authentication.py b/tests/test_authentication.py
index ecddda75e..35c1110d1 100644
--- a/tests/test_authentication.py
+++ b/tests/test_authentication.py
@@ -21,10 +21,9 @@
 from starlette.requests import HTTPConnection, Request
 from starlette.responses import JSONResponse, Response
 from starlette.routing import Route, WebSocketRoute
-from starlette.testclient import TestClient
 from starlette.websockets import WebSocket, WebSocketDisconnect
+from tests.types import TestClientFactory
 
-TestClientFactory = Callable[..., TestClient]
 AsyncEndpoint = Callable[..., Awaitable[Response]]
 SyncEndpoint = Callable[..., Response]
 
diff --git a/tests/test_background.py b/tests/test_background.py
index 846deecfd..cbffcc06a 100644
--- a/tests/test_background.py
+++ b/tests/test_background.py
@@ -1,13 +1,9 @@
-from typing import Callable
-
 import pytest
 
 from starlette.background import BackgroundTask, BackgroundTasks
 from starlette.responses import Response
-from starlette.testclient import TestClient
 from starlette.types import Receive, Scope, Send
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_async_task(test_client_factory: TestClientFactory) -> None:
diff --git a/tests/test_concurrency.py b/tests/test_concurrency.py
index aba3ceb1a..bac6814e4 100644
--- a/tests/test_concurrency.py
+++ b/tests/test_concurrency.py
@@ -1,5 +1,5 @@
 from contextvars import ContextVar
-from typing import Callable, Iterator
+from typing import Iterator
 
 import anyio
 import pytest
@@ -9,9 +9,7 @@
 from starlette.requests import Request
 from starlette.responses import Response
 from starlette.routing import Route
-from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 @pytest.mark.anyio
diff --git a/tests/test_convertors.py b/tests/test_convertors.py
index 72ee17a82..520c98767 100644
--- a/tests/test_convertors.py
+++ b/tests/test_convertors.py
@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Callable, Iterator
+from typing import Iterator
 
 import pytest
 
@@ -8,9 +8,7 @@
 from starlette.requests import Request
 from starlette.responses import JSONResponse
 from starlette.routing import Route, Router
-from starlette.testclient import TestClient
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 @pytest.fixture(scope="module", autouse=True)
diff --git a/tests/test_endpoints.py b/tests/test_endpoints.py
index eeb0f2322..96ad3c4ea 100644
--- a/tests/test_endpoints.py
+++ b/tests/test_endpoints.py
@@ -1,4 +1,4 @@
-from typing import Callable, Iterator
+from typing import Iterator
 
 import pytest
 
@@ -8,8 +8,7 @@
 from starlette.routing import Route, Router
 from starlette.testclient import TestClient
 from starlette.websockets import WebSocket
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 class Homepage(HTTPEndpoint):
@@ -50,7 +49,9 @@ def test_http_endpoint_route_method(client: TestClient) -> None:
     assert response.headers["allow"] == "GET"
 
 
-def test_websocket_endpoint_on_connect(test_client_factory: TestClientFactory) -> None:
+def test_websocket_endpoint_on_connect(
+    test_client_factory: TestClientFactory,
+) -> None:
     class WebSocketApp(WebSocketEndpoint):
         async def on_connect(self, websocket: WebSocket) -> None:
             assert websocket["subprotocols"] == ["soap", "wamp"]
@@ -137,7 +138,9 @@ async def on_receive(self, websocket: WebSocket, data: str) -> None:
             websocket.send_bytes(b"Hello world")
 
 
-def test_websocket_endpoint_on_default(test_client_factory: TestClientFactory) -> None:
+def test_websocket_endpoint_on_default(
+    test_client_factory: TestClientFactory,
+) -> None:
     class WebSocketApp(WebSocketEndpoint):
         encoding = None
 
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
index 401ad8212..ca4e1d72b 100644
--- a/tests/test_exceptions.py
+++ b/tests/test_exceptions.py
@@ -1,5 +1,5 @@
 import warnings
-from typing import Callable, Generator
+from typing import Generator
 
 import pytest
 
@@ -10,8 +10,7 @@
 from starlette.routing import Route, Router, WebSocketRoute
 from starlette.testclient import TestClient
 from starlette.types import Receive, Scope, Send
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def raise_runtime_error(request: Request) -> None:
@@ -82,7 +81,9 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
 
 
 @pytest.fixture
-def client(test_client_factory: TestClientFactory) -> Generator[TestClient, None, None]:
+def client(
+    test_client_factory: TestClientFactory,
+) -> Generator[TestClient, None, None]:
     with test_client_factory(app) as client:
         yield client
 
diff --git a/tests/test_formparsers.py b/tests/test_formparsers.py
index ed2226878..8d97a0ba7 100644
--- a/tests/test_formparsers.py
+++ b/tests/test_formparsers.py
@@ -13,10 +13,8 @@
 from starlette.requests import Request
 from starlette.responses import JSONResponse
 from starlette.routing import Mount
-from starlette.testclient import TestClient
 from starlette.types import ASGIApp, Receive, Scope, Send
-
-TestClientFactory = typing.Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 class ForceMultipartDict(typing.Dict[typing.Any, typing.Any]):
diff --git a/tests/test_requests.py b/tests/test_requests.py
index d8e2e9477..be31074c0 100644
--- a/tests/test_requests.py
+++ b/tests/test_requests.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import sys
-from typing import Any, Callable, Iterator
+from typing import Any, Iterator
 
 import anyio
 import pytest
@@ -9,10 +9,8 @@
 from starlette.datastructures import Address, State
 from starlette.requests import ClientDisconnect, Request
 from starlette.responses import JSONResponse, PlainTextResponse, Response
-from starlette.testclient import TestClient
 from starlette.types import Message, Receive, Scope, Send
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_request_url(test_client_factory: TestClientFactory) -> None:
@@ -133,7 +131,9 @@ async def app(scope: Scope, receive: Receive, send: Send) -> None:
     assert response.json() == {"form": {"abc": "123 @"}}
 
 
-def test_request_form_context_manager(test_client_factory: TestClientFactory) -> None:
+def test_request_form_context_manager(
+    test_client_factory: TestClientFactory,
+) -> None:
     async def app(scope: Scope, receive: Receive, send: Send) -> None:
         request = Request(scope, receive)
         async with request.form() as form:
diff --git a/tests/test_responses.py b/tests/test_responses.py
index fa3c1009f..dfd56cf43 100644
--- a/tests/test_responses.py
+++ b/tests/test_responses.py
@@ -5,7 +5,7 @@
 import time
 from http.cookies import SimpleCookie
 from pathlib import Path
-from typing import AsyncIterator, Callable, Iterator
+from typing import AsyncIterator, Iterator
 
 import anyio
 import pytest
@@ -23,8 +23,7 @@
 )
 from starlette.testclient import TestClient
 from starlette.types import Message, Receive, Scope, Send
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_text_response(test_client_factory: TestClientFactory) -> None:
@@ -532,7 +531,9 @@ def test_streaming_response_unknown_size(
     assert "content-length" not in response.headers
 
 
-def test_streaming_response_known_size(test_client_factory: TestClientFactory) -> None:
+def test_streaming_response_known_size(
+    test_client_factory: TestClientFactory,
+) -> None:
     app = StreamingResponse(
         content=iter(["hello", "world"]), headers={"content-length": "10"}
     )
diff --git a/tests/test_routing.py b/tests/test_routing.py
index b75fc47f0..e26295a1f 100644
--- a/tests/test_routing.py
+++ b/tests/test_routing.py
@@ -17,8 +17,7 @@
 from starlette.testclient import TestClient
 from starlette.types import ASGIApp, Message, Receive, Scope, Send
 from starlette.websockets import WebSocket, WebSocketDisconnect
-
-TestClientFactory = typing.Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def homepage(request: Request) -> Response:
diff --git a/tests/test_schemas.py b/tests/test_schemas.py
index e00b2b8de..f4a5b4ad9 100644
--- a/tests/test_schemas.py
+++ b/tests/test_schemas.py
@@ -1,20 +1,16 @@
-from typing import Callable
-
 from starlette.applications import Starlette
 from starlette.endpoints import HTTPEndpoint
 from starlette.requests import Request
 from starlette.responses import Response
 from starlette.routing import Host, Mount, Route, Router, WebSocketRoute
 from starlette.schemas import SchemaGenerator
-from starlette.testclient import TestClient
 from starlette.websockets import WebSocket
+from tests.types import TestClientFactory
 
 schemas = SchemaGenerator(
     {"openapi": "3.0.0", "info": {"title": "Example API", "version": "1.0"}}
 )
 
-TestClientFactory = Callable[..., TestClient]
-
 
 def ws(session: WebSocket) -> None:
     """ws"""
diff --git a/tests/test_staticfiles.py b/tests/test_staticfiles.py
index d20bb7ef7..aa2dd0aa4 100644
--- a/tests/test_staticfiles.py
+++ b/tests/test_staticfiles.py
@@ -16,9 +16,7 @@
 from starlette.responses import Response
 from starlette.routing import Mount
 from starlette.staticfiles import StaticFiles
-from starlette.testclient import TestClient
-
-TestClientFactory = typing.Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_staticfiles(tmpdir: Path, test_client_factory: TestClientFactory) -> None:
diff --git a/tests/test_templates.py b/tests/test_templates.py
index 10a1366bc..8e344f331 100644
--- a/tests/test_templates.py
+++ b/tests/test_templates.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import os
-import typing
 from pathlib import Path
 from unittest import mock
 
@@ -16,9 +15,7 @@
 from starlette.responses import Response
 from starlette.routing import Route
 from starlette.templating import Jinja2Templates
-from starlette.testclient import TestClient
-
-TestClientFactory = typing.Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_templates(tmpdir: Path, test_client_factory: TestClientFactory) -> None:
diff --git a/tests/test_testclient.py b/tests/test_testclient.py
index 4ed1ced9a..d8ad4d783 100644
--- a/tests/test_testclient.py
+++ b/tests/test_testclient.py
@@ -4,7 +4,7 @@
 import sys
 from asyncio import Task, current_task as asyncio_current_task
 from contextlib import asynccontextmanager
-from typing import Any, AsyncGenerator, Callable
+from typing import Any, AsyncGenerator
 
 import anyio
 import anyio.lowlevel
@@ -20,8 +20,7 @@
 from starlette.testclient import ASGIInstance, TestClient
 from starlette.types import ASGIApp, Receive, Scope, Send
 from starlette.websockets import WebSocket, WebSocketDisconnect
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def mock_service_endpoint(request: Request) -> JSONResponse:
@@ -212,7 +211,7 @@ async def inner(receive: Receive, send: Send) -> None:
 
         return inner
 
-    client = test_client_factory(app)
+    client = test_client_factory(app)  # type: ignore
     response = client.get("/")
     assert response.text == "Hello, world!"
 
@@ -252,13 +251,15 @@ async def asgi(receive: Receive, send: Send) -> None:
 
         return asgi
 
-    client = test_client_factory(app)
+    client = test_client_factory(app)  # type: ignore
     with client.websocket_connect("/") as websocket:
         data = websocket.receive_json()
         assert data == {"message": "test"}
 
 
-def test_websocket_not_block_on_close(test_client_factory: TestClientFactory) -> None:
+def test_websocket_not_block_on_close(
+    test_client_factory: TestClientFactory,
+) -> None:
     def app(scope: Scope) -> ASGIInstance:
         async def asgi(receive: Receive, send: Send) -> None:
             websocket = WebSocket(scope, receive=receive, send=send)
@@ -268,7 +269,7 @@ async def asgi(receive: Receive, send: Send) -> None:
 
         return asgi
 
-    client = test_client_factory(app)
+    client = test_client_factory(app)  # type: ignore
     with client.websocket_connect("/") as websocket:
         ...
     assert websocket.should_close.is_set()
diff --git a/tests/test_websockets.py b/tests/test_websockets.py
index 854c26914..d7488c479 100644
--- a/tests/test_websockets.py
+++ b/tests/test_websockets.py
@@ -1,5 +1,5 @@
 import sys
-from typing import Any, Callable, MutableMapping
+from typing import Any, MutableMapping
 
 import anyio
 import pytest
@@ -7,11 +7,10 @@
 
 from starlette import status
 from starlette.responses import Response
-from starlette.testclient import TestClient, WebSocketDenialResponse
+from starlette.testclient import WebSocketDenialResponse
 from starlette.types import Message, Receive, Scope, Send
 from starlette.websockets import WebSocket, WebSocketDisconnect, WebSocketState
-
-TestClientFactory = Callable[..., TestClient]
+from tests.types import TestClientFactory
 
 
 def test_websocket_url(test_client_factory: TestClientFactory) -> None:
@@ -207,7 +206,9 @@ async def app(scope: Scope, receive: Receive, send: Send) -> None:
         assert data == {"message": {"hello": "world"}}
 
 
-def test_websocket_concurrency_pattern(test_client_factory: TestClientFactory) -> None:
+def test_websocket_concurrency_pattern(
+    test_client_factory: TestClientFactory,
+) -> None:
     stream_send: ObjectSendStream[MutableMapping[str, Any]]
     stream_receive: ObjectReceiveStream[MutableMapping[str, Any]]
     stream_send, stream_receive = anyio.create_memory_object_stream()
@@ -379,7 +380,9 @@ async def app(scope: Scope, receive: Receive, send: Send) -> None:
     assert exc.value.code == status.WS_1000_NORMAL_CLOSURE
 
 
-def test_send_response_duplicate_start(test_client_factory: TestClientFactory) -> None:
+def test_send_response_duplicate_start(
+    test_client_factory: TestClientFactory,
+) -> None:
     async def app(scope: Scope, receive: Receive, send: Send) -> None:
         websocket = WebSocket(scope, receive=receive, send=send)
         msg = await websocket.receive()
@@ -564,7 +567,9 @@ async def app(scope: Scope, receive: Receive, send: Send) -> None:
             pass  # pragma: nocover
 
 
-def test_receive_bytes_before_accept(test_client_factory: TestClientFactory) -> None:
+def test_receive_bytes_before_accept(
+    test_client_factory: TestClientFactory,
+) -> None:
     async def app(scope: Scope, receive: Receive, send: Send) -> None:
         websocket = WebSocket(scope, receive=receive, send=send)
         await websocket.receive_bytes()
diff --git a/tests/types.py b/tests/types.py
new file mode 100644
index 000000000..4ab704159
--- /dev/null
+++ b/tests/types.py
@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from typing import Protocol
+
+import httpx
+
+from starlette.testclient import TestClient
+from starlette.types import ASGIApp
+
+
+class TestClientFactory(Protocol):  # pragma: no cover
+    __test__ = False  # type: ignore
+
+    def __call__(
+        self,
+        app: ASGIApp,
+        base_url: str = "http://testserver",
+        raise_server_exceptions: bool = True,
+        root_path: str = "",
+        cookies: httpx._types.CookieTypes | None = None,
+        headers: dict[str, str] | None = None,
+        follow_redirects: bool = True,
+    ) -> TestClient:
+        ...