Add error handling for process communication failures in IF save/restore

src/mudlib/if_session.py

@@ -111,27 +111,30 @@ class IFSession:
         if not self.process or not self.process.stdin:
             return "error: game not running"
 
-        # Ensure save directory exists
-        self._ensure_save_dir()
+        try:
+            # Ensure save directory exists
+            self._ensure_save_dir()
 
-        # Send "save" command to dfrotz
-        self.process.stdin.write(b"save\n")
-        await self.process.stdin.drain()
+            # Send "save" command to dfrotz
+            self.process.stdin.write(b"save\n")
+            await self.process.stdin.drain()
 
-        # Read filename prompt
-        await self._read_response()
+            # Read filename prompt
+            await self._read_response()
 
-        # Send save file path
-        save_path_str = str(self.save_path)
-        self.process.stdin.write(f"{save_path_str}\n".encode())
-        await self.process.stdin.drain()
+            # Send save file path
+            save_path_str = str(self.save_path)
+            self.process.stdin.write(f"{save_path_str}\n".encode())
+            await self.process.stdin.drain()
 
-        # Read confirmation
-        confirmation = await self._read_response()
+            # Read confirmation
+            confirmation = await self._read_response()
 
-        # Mark as saved
-        self._saved = True
-        return confirmation
+            # Mark as saved
+            self._saved = True
+            return confirmation
+        except Exception as e:
+            return f"error: save failed ({e})"
 
     async def _do_restore(self) -> str:
         """Restore game state from disk. Returns game text or empty string."""
@@ -142,21 +145,25 @@ class IFSession:
         if not self.process or not self.process.stdin:
             return ""
 
-        # Send "restore" command to dfrotz
-        self.process.stdin.write(b"restore\n")
-        await self.process.stdin.drain()
+        try:
+            # Send "restore" command to dfrotz
+            self.process.stdin.write(b"restore\n")
+            await self.process.stdin.drain()
 
-        # Read filename prompt
-        await self._read_response()
+            # Read filename prompt
+            await self._read_response()
 
-        # Send save file path
-        save_path_str = str(self.save_path)
-        self.process.stdin.write(f"{save_path_str}\n".encode())
-        await self.process.stdin.drain()
+            # Send save file path
+            save_path_str = str(self.save_path)
+            self.process.stdin.write(f"{save_path_str}\n".encode())
+            await self.process.stdin.drain()
 
-        # Read game text response
-        game_text = await self._read_response()
-        return game_text
+            # Read game text response
+            game_text = await self._read_response()
+            return game_text
+        except Exception:
+            # If restore fails, return empty string (player starts fresh)
+            return ""
 
     async def _read_response(self) -> str:
         """Read dfrotz output until the '>' prompt appears."""

tests/test_if_session.py

@@ -683,3 +683,96 @@ async def test_regular_input_resets_save_flag(tmp_path):
         call for call in mock_process.stdin.write.call_args_list if call[0][0] == b"save\n"
     ]
     assert len(save_calls) == 2, "should be able to save again after regular input"
+
+
+@pytest.mark.asyncio
+async def test_do_save_handles_process_communication_failure(tmp_path):
+    """_do_save() returns error message when process communication fails."""
+    player = MagicMock()
+    player.name = "tester"
+    session = IFSession(player, "/path/to/zork.z5", "zork")
+    session._data_dir = tmp_path
+
+    # Mock process that raises an exception
+    mock_process = MagicMock()
+    mock_process.stdin = MagicMock()
+    mock_process.stdin.write = MagicMock(side_effect=BrokenPipeError("process died"))
+    session.process = mock_process
+
+    result = await session._do_save()
+
+    assert "error" in result.lower()
+    assert "save" in result.lower() or "failed" in result.lower()
+
+
+@pytest.mark.asyncio
+async def test_do_save_handles_stdout_read_failure(tmp_path):
+    """_do_save() returns error message when reading response fails."""
+    player = MagicMock()
+    player.name = "tester"
+    session = IFSession(player, "/path/to/zork.z5", "zork")
+    session._data_dir = tmp_path
+
+    # Mock process where writing succeeds but reading fails
+    mock_process = MagicMock()
+    mock_process.stdin = MagicMock()
+    mock_process.stdin.write = MagicMock()
+    mock_process.stdin.drain = AsyncMock()
+    mock_process.stdout = AsyncMock()
+    mock_process.stdout.read = AsyncMock(side_effect=OSError("read failed"))
+    session.process = mock_process
+
+    result = await session._do_save()
+
+    assert "error" in result.lower()
+
+
+@pytest.mark.asyncio
+async def test_do_restore_handles_process_communication_failure(tmp_path):
+    """_do_restore() returns empty string when process communication fails."""
+    player = MagicMock()
+    player.name = "tester"
+    session = IFSession(player, "/path/to/zork.z5", "zork")
+    session._data_dir = tmp_path
+
+    # Create a save file so we get past the existence check
+    session._ensure_save_dir()
+    session.save_path.write_text("fake save data")
+
+    # Mock process that raises an exception
+    mock_process = MagicMock()
+    mock_process.stdin = MagicMock()
+    mock_process.stdin.write = MagicMock(side_effect=BrokenPipeError("process died"))
+    session.process = mock_process
+
+    result = await session._do_restore()
+
+    # Should return empty string on failure (player starts fresh)
+    assert result == ""
+
+
+@pytest.mark.asyncio
+async def test_do_restore_handles_stdout_read_failure(tmp_path):
+    """_do_restore() returns empty string when reading response fails."""
+    player = MagicMock()
+    player.name = "tester"
+    session = IFSession(player, "/path/to/zork.z5", "zork")
+    session._data_dir = tmp_path
+
+    # Create a save file
+    session._ensure_save_dir()
+    session.save_path.write_text("fake save data")
+
+    # Mock process where writing succeeds but reading fails
+    mock_process = MagicMock()
+    mock_process.stdin = MagicMock()
+    mock_process.stdin.write = MagicMock()
+    mock_process.stdin.drain = AsyncMock()
+    mock_process.stdout = AsyncMock()
+    mock_process.stdout.read = AsyncMock(side_effect=OSError("read failed"))
+    session.process = mock_process
+
+    result = await session._do_restore()
+
+    # Should return empty string on failure (player starts fresh)
+    assert result == ""