fix(time): exit with one line on an invalid --local-timezone (#5001)

src/time/src/mcp_server_time/server.py

@@ -2,9 +2,10 @@
 from importlib.metadata import version
 from enum import Enum
 import json
+import sys
 from typing import Sequence
 
-from zoneinfo import ZoneInfo
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 from tzlocal import get_localzone_name  # ← returns "Europe/Paris", etc.
 
 from mcp.server import Server
@@ -139,6 +140,18 @@ def convert_time(
 async def serve(local_timezone: str | None = None) -> None:
     server = Server("mcp-time", version=SERVER_VERSION)
     time_server = TimeServer()
+    if local_timezone:
+        # Fail before the transport opens, with one line naming the bad value
+        # rather than a traceback. zoneinfo raises a different type per kind of
+        # bad key (unknown name, a tzdata directory, a path, a null byte), and
+        # its messages can carry a filesystem path, so none of them is shown.
+        try:
+            ZoneInfo(local_timezone)
+        except (ZoneInfoNotFoundError, ValueError, OSError):
+            sys.exit(
+                f"Error: invalid --local-timezone {local_timezone!r}: "
+                "not a known IANA timezone name"
+            )
     local_tz = str(get_local_tz(local_timezone))
 
     @server.list_tools()

src/time/tests/test_entrypoints.py

@@ -10,6 +10,7 @@
 import os
 import runpy
 import shutil
+import subprocess
 import sys
 from pathlib import Path
 from unittest.mock import AsyncMock, MagicMock, patch
@@ -114,3 +115,22 @@ async def test_console_script_boots_over_stdio() -> None:
     )
     assert [tool.name for tool in tools.tools] == ["get_current_time", "convert_time"]
     assert result.model_dump(by_alias=True, mode="json")["isError"] is False
+
+
+def test_console_script_rejects_an_invalid_local_timezone() -> None:
+    # #5001: one line on stderr naming the value, a non-zero exit, and no
+    # traceback.
+    script = shutil.which("mcp-server-time", path=str(Path(sys.executable).parent))
+    assert script is not None, "the console script is not installed in this venv"
+    proc = subprocess.run(
+        [script, "--local-timezone", "Not/AZone"],
+        stdin=subprocess.DEVNULL,
+        capture_output=True,
+        text=True,
+        timeout=60,
+    )
+    assert proc.returncode == 1
+    assert proc.stdout == ""
+    assert proc.stderr.splitlines() == [
+        "Error: invalid --local-timezone 'Not/AZone': not a known IANA timezone name"
+    ]

src/time/tests/test_protocol.py

@@ -34,7 +34,6 @@
 from mcp import ClientSession
 from mcp.shared.memory import create_client_server_memory_streams
 from pydantic import BaseModel
-from zoneinfo import ZoneInfoNotFoundError
 
 from mcp_server_time.server import serve
 
@@ -236,16 +235,31 @@ async def test_empty_local_timezone_override_is_treated_as_absent() -> None:
     assert result == {"tools": expected_tools("Africa/Cairo")}
 
 
-# KNOWN BUG #5001: an invalid --local-timezone crashes serve() with a traceback instead of a clean error; the fix changes this assertion.
-async def test_invalid_local_timezone_fails_before_the_transport_opens() -> None:
-    # An unknown `--local-timezone` raises out of `serve()` itself, before
-    # stdio is opened: the process dies with a traceback instead of starting.
+@pytest.mark.parametrize(
+    "local_timezone",
+    [
+        "Not/AZone",  # unknown name: ZoneInfoNotFoundError
+        "America",  # a tzdata directory, not a zone: OSError
+        "../etc/passwd",  # outside TZPATH: ValueError
+    ],
+)
+async def test_invalid_local_timezone_fails_before_the_transport_opens(
+    local_timezone: str,
+) -> None:
+    # An invalid `--local-timezone` stops `serve()` before stdio is opened,
+    # with a one-line message naming the value and a non-zero exit, rather
+    # than a traceback (#5001). A `SystemExit` whose code is a string prints
+    # that string to stderr and exits 1.
     def unexpected_stdio_server():
         raise AssertionError("stdio_server must not be reached")
 
     with patch("mcp_server_time.server.stdio_server", unexpected_stdio_server):
-        with pytest.raises(ZoneInfoNotFoundError, match="Not/AZone"):
-            await serve("Not/AZone")
+        with pytest.raises(SystemExit) as exit_info:
+            await serve(local_timezone)
+    assert exit_info.value.code == (
+        f"Error: invalid --local-timezone {local_timezone!r}: "
+        "not a known IANA timezone name"
+    )
 
 
 # ---------------------------------------------------------------------------