fix: use re.match instead of re.search for mounted app path (#3501) (#…

…3511)

litestar/_asgi/routing_trie/traversal.py

@@ -136,8 +136,8 @@ def parse_path_to_route(
             asgi_app, handler = parse_node_handlers(node=root_node.children[path], method=method)
             return asgi_app, handler, path, {}
 
-        if mount_paths_regex and (match := mount_paths_regex.search(path)):
-            mount_path = path[match.start() : match.end()]
+        if mount_paths_regex and (match := mount_paths_regex.match(path)):
+            mount_path = path[: match.end()]
             mount_node = mount_routes[mount_path]
             remaining_path = path[match.end() :]
             # since we allow regular handlers under static paths, we must validate that the request does not match

tests/unit/test_asgi/test_routing_trie/test_traversal.py

@@ -0,0 +1,93 @@
+from typing import Any
+
+from litestar import Router, asgi, get
+from litestar.response.base import ASGIResponse
+from litestar.status_codes import HTTP_404_NOT_FOUND
+from litestar.testing import create_test_client
+
+
+def test_parse_path_to_route_mounted_app_path_root() -> None:
+    # test that paths are correctly dispatched to handlers when mounting an app
+    # and other handlers to root path /
+
+    @asgi("/foobar", is_mount=True)
+    async def mounted_handler(scope: Any, receive: Any, send: Any) -> None:
+        response = ASGIResponse(body="mounted")
+        await response(scope, receive, send)
+
+    @get("/{number:int}/foobar/")
+    async def parametrized_handler() -> str:
+        return "parametrized"
+
+    @get("/static/foobar/")
+    async def static_handler() -> str:
+        return "static"
+
+    with create_test_client(
+        [
+            mounted_handler,
+            parametrized_handler,
+            static_handler,
+        ]
+    ) as client:
+        response = client.get("/foobar")
+        assert response.text == "mounted"
+
+        response = client.get("/foobar/123/")
+        assert response.text == "mounted"
+
+        response = client.get("/123/foobar/")
+        assert response.text == "parametrized"
+
+        response = client.get("/static/foobar/")
+        assert response.text == "static"
+
+        response = client.get("/unknown/foobar/")
+        assert response.status_code == HTTP_404_NOT_FOUND
+
+
+def test_parse_path_to_route_mounted_app_path_router() -> None:
+    # test that paths are correctly dispatched to handlers when mounting an app
+    # and other handlers inside subrouter
+
+    @asgi("/foobar", is_mount=True)
+    async def mounted_handler(scope: Any, receive: Any, send: Any) -> None:
+        response = ASGIResponse(body="mounted")
+        await response(scope, receive, send)
+
+    @get("/{number:int}/foobar/")
+    async def parametrized_handler() -> str:
+        return "parametrized"
+
+    @get("/static/foobar/")
+    async def static_handler() -> str:
+        return "static"
+
+    sub_router = Router(
+        path="/sub",
+        route_handlers=[
+            mounted_handler,
+            parametrized_handler,
+            static_handler,
+        ],
+    )
+    base_router = Router(path="/base", route_handlers=[sub_router])
+
+    with create_test_client([base_router]) as client:
+        response = client.get("/foobar")
+        assert response.status_code == HTTP_404_NOT_FOUND
+
+        response = client.get("/base/sub/foobar")
+        assert response.text == "mounted"
+
+        response = client.get("/base/sub/foobar/123/")
+        assert response.text == "mounted"
+
+        response = client.get("/base/sub/123/foobar/")
+        assert response.text == "parametrized"
+
+        response = client.get("/base/sub/static/foobar/")
+        assert response.text == "static"
+
+        response = client.get("/base/sub/unknown/foobar/")
+        assert response.status_code == HTTP_404_NOT_FOUND