Accept engines that require an interpreter (#1023)

config.yml.default

@@ -4,6 +4,9 @@ url: "https://lichess.org/"        # Lichess base URL.
 engine:                            # Engine settings.
   dir: "./engines/"                # Directory containing the engine. This can be an absolute path or one relative to lichess-bot/.
   name: "engine_name"              # Binary name of the engine to use.
+# interpreter: "java"
+# interpreter_options:
+#   - "-jar"
   working_dir: ""                  # Directory where the chess engine will read and write files. If blank or missing, the current directory is used.
                                    # NOTE: If working_dir is set, the engine will look for files and directories relative to this directory, not where lichess-bot was launched. Absolute paths are unaffected.
   protocol: "uci"                  # "uci", "xboard" or "homemade"

lib/config.py

@@ -148,6 +148,9 @@ def insert_default_values(CONFIG: CONFIG_DICT_TYPE) -> None:
     set_config_default(CONFIG, key="pgn_directory", default=None)
     set_config_default(CONFIG, key="pgn_file_grouping", default="game", force_empty_values=True)
     set_config_default(CONFIG, key="max_takebacks_accepted", default=0, force_empty_values=True)
+    set_config_default(CONFIG, "engine", key="interpreter", default=None)
+    set_config_default(CONFIG, "engine", key="interpreter_options", default=[], force_empty_values=True)
+    change_value_to_list(CONFIG, "engine", key="interpreter_options")
     set_config_default(CONFIG, "engine", key="working_dir", default=os.getcwd(), force_empty_values=True)
     set_config_default(CONFIG, "engine", key="silence_stderr", default=False)
     set_config_default(CONFIG, "engine", "draw_or_resign", key="offer_draw_enabled", default=False)

lib/engine_wrapper.py

@@ -44,7 +44,11 @@ def create_engine(engine_config: Configuration, game: Optional[model.Game] = Non
     cfg = engine_config.engine
     engine_path = os.path.abspath(os.path.join(cfg.dir, cfg.name))
     engine_type = cfg.protocol
-    commands = [engine_path]
+    commands = []
+    if cfg.interpreter:
+        commands.append(cfg.interpreter)
+        commands.extend(cfg.interpreter_options)
+    commands.append(engine_path)
     if cfg.engine_options:
         for k, v in cfg.engine_options.items():
             commands.append(f"--{k}={v}" if v is not None else f"--{k}")

test_bot/test_bot.py

@@ -31,7 +31,7 @@
 
 
 def download_sf() -> None:
-    """Download Stockfish 15."""
+    """Download Stockfish 16."""
     if os.path.exists(stockfish_path):
         return
 
@@ -284,7 +284,7 @@ def test_homemade() -> None:
                                        "bo vs b - zzzzzzzz.pgn"))
 
 
-@pytest.mark.timeout(30, method="thread")
+@pytest.mark.timeout(60, method="thread")
 def test_buggy_engine() -> None:
     """Test lichess-bot with an engine that causes a timeout error within python-chess."""
     with open("./config.yml.default") as file:
@@ -294,15 +294,17 @@ def test_buggy_engine() -> None:
 
     def engine_path(CONFIG: CONFIG_DICT_TYPE) -> str:
         dir: str = CONFIG["engine"]["dir"]
-        name: str = CONFIG["engine"]["name"]
-        return os.path.join(dir, name)
-
-    if platform == "win32":
-        CONFIG["engine"]["name"] = "buggy_engine.bat"
-    else:
-        CONFIG["engine"]["name"] = "buggy_engine"
-        st = os.stat(engine_path(CONFIG))
-        os.chmod(engine_path(CONFIG), st.st_mode | stat.S_IEXEC)
+        name: str = CONFIG["engine"]["name"].removesuffix(".py")
+        path = os.path.join(dir, name)
+        if platform == "win32":
+            path += ".bat"
+        else:
+            st = os.stat(path)
+            os.chmod(path, st.st_mode | stat.S_IEXEC)
+        return path
+
+    CONFIG["engine"]["name"] = "buggy_engine.py"
+    CONFIG["engine"]["interpreter"] = "python" if platform == "win32" else "python3"
     CONFIG["engine"]["uci_options"] = {"go_commands": {"movetime": 100}}
     CONFIG["pgn_directory"] = "TEMP/bug_game_record"
 

wiki/Configure-lichess-bot.md

@@ -2,7 +2,9 @@
 There are many possible options within `config.yml` for configuring lichess-bot.
 
 ## Engine options
-- `protocol`: Specify which protocol your engine uses. Choices are
+- `interpreter`: Specify whether your engine requires an interpreter to run (e.g. `java`, `python`).
+- `interpreter_options`: A list of options passed to the interpreter (e.g. `-jar` for `java`).
+- `protocol`: Specify which protocol your engine uses. Choices are:
     1. `"uci"` for the [Universal Chess Interface](https://wbec-ridderkerk.nl/html/UCIProtocol.html)
     2. `"xboard"` for the XBoard/WinBoard/[Chess Engine Communication Protocol](https://www.gnu.org/software/xboard/engine-intf.html)
     3. `"homemade"` if you want to write your own engine in Python within lichess-bot. See [**Create a homemade engine**](https://github.com/lichess-bot-devs/lichess-bot/wiki/Create-a-homemade-engine).