Check for ROMs at beginning of generation (#475)

Main.py

@@ -93,6 +93,8 @@ def main(args, seed=None, baked_server_options: Optional[Dict[str, object]] = No
                         f"Location IDs: {min(cls.location_id_to_name):{numlength}} - "
                         f"{max(cls.location_id_to_name):{numlength}}")
 
+    AutoWorld.call_stage(world, "assert_generate")
+
     AutoWorld.call_all(world, "generate_early")
 
     logger.info('')

docs/api.md

@@ -426,6 +426,9 @@ In addition, the following methods can be implemented and attributes can be set
 * `required_client_version: Tuple(int, int, int)`
   Client version as tuple of 3 ints to make sure the client is compatible to
   this world (e.g. implements all required features) when connecting.
+* `assert_generate(cls, world)` is a class method called at the start of
+  generation to check the existence of prerequisite files, usually a ROM for
+  games which require one.
 
 #### generate_early
 

worlds/AutoWorld.py

@@ -171,6 +171,12 @@ class World(metaclass=AutoWorldRegister):
     # can also be implemented as a classmethod and called "stage_<original_name>",
     # in that case the MultiWorld object is passed as an argument and it gets called once for the entire multiworld.
     # An example of this can be found in alttp as stage_pre_fill
+    @classmethod
+    def assert_generate(cls) -> None:
+        """Checks that a game is capable of generating, usually checks for some base file like a ROM.
+        Not run for unittests since they don't produce output"""
+        pass
+
     def generate_early(self) -> None:
         pass
 

worlds/alttp/__init__.py

@@ -56,6 +56,12 @@ class ALTTPWorld(World):
         self.has_progressive_bows = False
         super(ALTTPWorld, self).__init__(*args, **kwargs)
 
+    @classmethod
+    def stage_assert_generate(cls, world):
+        rom_file = get_base_rom_path()
+        if not os.path.exists(rom_file):
+            raise FileNotFoundError(rom_file)
+
     def generate_early(self):
         player = self.player
         world = self.world

worlds/oot/__init__.py

@@ -89,6 +89,10 @@ class OOTWorld(World):
         self.hint_data_available = threading.Event()
         super(OOTWorld, self).__init__(world, player)
 
+    @classmethod
+    def stage_assert_generate(cls, world: MultiWorld):
+        rom = Rom(file=get_options()['oot_options']['rom_file'])
+
     def generate_early(self):
         # Player name MUST be at most 16 bytes ascii-encoded, otherwise won't write to ROM correctly
         if len(bytes(self.world.get_player_name(self.player), 'ascii')) > 16:

worlds/sm/__init__.py

@@ -83,6 +83,12 @@ class SMWorld(World):
         self.rom_name_available_event = threading.Event()
         super().__init__(world, player)
 
+    @classmethod
+    def stage_assert_generate(cls, world):
+        rom_file = get_base_rom_path()
+        if not os.path.exists(rom_file):
+            raise FileNotFoundError(rom_file)
+
     def generate_early(self):
         Logic.factory('vanilla')
 

worlds/smz3/__init__.py

@@ -60,6 +60,10 @@ class SMZ3World(World):
         self.unreachable = []
         super().__init__(world, player)
 
+    @classmethod
+    def stage_assert_generate(cls, world):
+        base_combined_rom = get_base_rom_bytes()
+
     def generate_early(self):
         config = Config({})
         config.GameMode = GameMode.Multiworld

worlds/soe/__init__.py

@@ -175,6 +175,12 @@ class SoEWorld(World):
         res.trap = item.type == pyevermizer.CHECK_TRAP
         return res
 
+    @classmethod
+    def stage_assert_generate(cls, world):
+        rom_file = get_base_rom_path()
+        if not os.path.exists(rom_file):
+            raise FileNotFoundError(rom_file)
+
     def create_regions(self):
         # TODO: generate *some* regions from locations' requirements?
         r = Region('Menu', RegionType.Generic, 'Menu', self.player, self.world)