fix: prevent generator hang and reject negative floor ids

requirements.txt

@@ -6,4 +6,5 @@ pylint~=4.1.3
 flake8~=7.4.1
 mypy~=2.4.0
 pillow~=13.0.0
-pytest~=9.1.1
+pytest~=9.1.1
+httpx~=0.28.1

src/controller.py

@@ -3,7 +3,7 @@
 """
 import secrets
 
-from fastapi import FastAPI
+from fastapi import FastAPI, Path
 from starlette.responses import FileResponse
 from fastapi.middleware.cors import CORSMiddleware
 
@@ -30,7 +30,7 @@ async def root():
 
 
 @app.get(_GENERATE + "/{floor_id}")
-async def generate_with_id(floor_id: int) -> FileResponse:
+async def generate_with_id(floor_id: int = Path(ge=0)) -> FileResponse:
     """
     This endpoint generates a floor with the given id
     and returns it in a FileResponse as a json file.
@@ -46,7 +46,9 @@ async def generate_with_id(floor_id: int) -> FileResponse:
 
 
 @app.get(_GENERATE + "/{floor_id}/{seed}")
-async def generate_with_id_and_seed(floor_id: int, seed: str) -> FileResponse:
+async def generate_with_id_and_seed(
+    floor_id: int = Path(ge=0), seed: str = Path()
+) -> FileResponse:
     """
     This endpoint generates a floor with the given id
     and seed and returns it in a FileResponse as a json file.

src/generators/generator.py

@@ -36,8 +36,10 @@ def __init__(
         Creates a new generator with the given arguments.
         @param seed: seed for generating the floor
         @param output_file_name: name for the outputfile
-        @param stage_id: id for the floor
+        @param stage_id: id for the floor (must be 0 or greater)
         """
+        if stage_id < 0:
+            raise ValueError(f"stage_id must be 0 or greater, got {stage_id}")
         self._stage_id = stage_id
         self._seed = seed
         self._output_file_name = output_file_name
@@ -336,18 +338,15 @@ def place_super_secret_room(self) -> None:
     def place_secret_room(self) -> None:
         """
         Places a secret room on the floor.
+        If no valid position exists, no secret room is placed.
         """
         floor = self._floor
-        secret_room_placed = False
         neighbour_rooms = 3
-        while not secret_room_placed:
+        while neighbour_rooms > 0:
             for room in reversed(floor.get_rooms()):
                 # Check all neighbours of the room
-                secret_room_placed = self._check_directions_for_secret_room(
-                    room, neighbour_rooms
-                )
-                if secret_room_placed:
-                    break
+                if self._check_directions_for_secret_room(room, neighbour_rooms):
+                    return
             neighbour_rooms -= 1
 
     def _check_directions_for_secret_room(

test/controller_test.py

@@ -0,0 +1,26 @@
+"""Unit tests for the FastAPI controller."""
+
+import unittest
+
+from fastapi.testclient import TestClient
+
+import controller
+
+
+class ControllerTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self._client = TestClient(controller.app)
+
+    def test_negative_floor_id_is_rejected(self):
+        response = self._client.get("/gen/-1")
+
+        self.assertEqual(422, response.status_code)
+
+    def test_negative_floor_id_with_seed_is_rejected(self):
+        response = self._client.get("/gen/-1/abc")
+
+        self.assertEqual(422, response.status_code)
+
+
+if __name__ == "__main__":
+    unittest.main()

test/generator_test.py

@@ -152,6 +152,26 @@ def test_to_json_round_trips_through_floor_from_json(self):
 
         self.assertEqual(self._generator._floor.get_rooms(), restored.get_rooms())
 
+    def test_negative_stage_id_is_rejected(self):
+        with self.assertRaises(ValueError):
+            Generator(seed="1", output_file_name="floor", stage_id=-1)
+
+    def test_generate_terminates_when_no_secret_room_position_exists(self):
+        # Seed "9" on floor 0 used to loop forever in place_secret_room.
+        generator = Generator(seed="9", output_file_name="floor", stage_id=0)
+
+        generator.generate()
+
+        self.assertGreater(len(generator._floor.get_rooms()), 0)
+
+    def test_generate_terminates_for_many_seeds_on_small_floors(self):
+        for stage_id in (0, 1):
+            for seed in range(200):
+                with self.subTest(stage_id=stage_id, seed=seed):
+                    Generator(
+                        seed=str(seed), output_file_name="floor", stage_id=stage_id
+                    ).generate()
+
     def test_save_writes_the_generated_floor_to_the_given_path(self):
         self._generator.generate()
         with tempfile.TemporaryDirectory() as tmp_dir: