tests

projects/fal/src/fal/api.py

@@ -826,11 +826,12 @@ async def not_found_exception_handler(request: Request, exc: HTTPException):
             # This is supposed to make it easier to understand to the user
             # that the error comes from the app and not our platform.
             try:
+                print(exc.detail, exc.detail == "Not Found")
                 if exc.detail == "Not Found":
                     return JSONResponse(
                         {"detail": f"Path {request.url.path} not found"}, 404
                     )
-            finally:
+            except Exception:
                 # If it's not a generic 404, just return the original message.
                 return JSONResponse({"detail": exc.detail}, 404)
 

projects/fal/tests/test_apps.py

@@ -1,6 +1,7 @@
 import time
 from typing import Generator
 
+import fastapi
 import pytest
 from fastapi import WebSocket
 from openapi_fal_rest.api.applications import app_metadata
@@ -79,6 +80,10 @@ def subtract(input: Input) -> Output:
         allow_origins=("*"),
     )
 
+    @app.exception_handler(404)
+    async def http_exception_handler(request, exc):
+        return fastapi.responses.JSONResponse("FAILED INSIDE THE APP", status_code=404)
+
     run(app, host="0.0.0.0", port=8080)
 
 
@@ -325,6 +330,27 @@ def test_app_no_serve_spec_metadata(
     ), f"openapi should not be present in metadata {metadata}"
 
 
+def test_404_response(
+    calculator_app: str, test_app: str, request: pytest.FixtureRequest
+):
+    try:
+        apps.run(test_app, path="/other", arguments={"lhs": 1, "rhs": 2})
+    except fastapi.HTTPException as e:
+        assert e.status_code == 404
+        assert "Path /other not found" in e.detail
+    else:
+        assert False, "Expected 404 response"
+
+    try:
+        apps.run(calculator_app, path="/other", arguments={"lhs": 1, "rhs": 2})
+    except fastapi.HTTPException as e:
+        assert e.status_code == 404
+        # Custom responses do not have the default message
+        assert "INSIDE APP" in e.detail
+    else:
+        assert False, "Expected 404 response"
+
+
 def test_app_update_app(aliased_app: tuple[str, str]):
     app_revision, app_alias = aliased_app