Fix optional route bug

starlette/routing.py

@@ -117,7 +117,12 @@ def compile_path(
 
         idx = match.end()
 
-    path_regex += re.escape(path[idx:]) + "$"
+    # Prevent the escape of ? for route ending with ?
+    if path[-1] == "?":
+        path_regex += re.escape(path[idx:-1]) + "?$"
+    else:
+        path_regex += re.escape(path[idx:]) + "$"
+
     path_format += path[idx:]
 
     return re.compile(path_regex), path_format, param_convertors

tests/test_routing.py

@@ -90,6 +90,12 @@ def path_with_parentheses(request):
     return JSONResponse({"int": number})
 
 
+# Route with chars that conflict with regex meta chars
+@app.route("/optional-path/?", name="optional-path")
+def optional_path(request):
+    return Response("Optional path reached.", media_type="text/plain")
+
+
 @app.websocket_route("/ws")
 async def websocket_endpoint(session):
     await session.accept()
@@ -162,6 +168,15 @@ def test_route_converters():
         == "/path-with-parentheses(7)"
     )
 
+    # Test optional path
+    response = client.get("/optional-path")
+    assert response.status_code == 200
+    assert response.text == "Optional path reached."
+
+    response = client.get("/optional-path/")
+    assert response.status_code == 200
+    assert response.text == "Optional path reached."
+
     # Test float conversion
     response = client.get("/float/25.5")
     assert response.status_code == 200