Add comprehensive test suite achieving 99% code coverage

Added 35 test files with 502 tests covering all Python modules including
API routes, ORM models, splendor game logic/TUI, heater controller,
weather service, NixOS installer, ZFS dataset management, and utilities.
Coverage improved from 11% to 99% (2540/2564 statements covered).

https://claude.ai/code/session_01SVzgLDUS1Cdc4eh1ijETTh

tests/test_heater_serve.py

@@ -0,0 +1,103 @@
+"""Tests for heater/main.py serve function and lifespan."""
+
+from __future__ import annotations
+
+import sys
+from unittest.mock import MagicMock, patch
+
+import pytest
+from click.exceptions import Exit
+
+from python.heater.models import DeviceConfig
+
+
+def test_serve_missing_params() -> None:
+    """Test serve raises when device params are missing."""
+    mock_tinytuya = MagicMock()
+    with patch.dict(sys.modules, {"tinytuya": mock_tinytuya}):
+        if "python.heater.controller" in sys.modules:
+            del sys.modules["python.heater.controller"]
+        if "python.heater.main" in sys.modules:
+            del sys.modules["python.heater.main"]
+        from python.heater.main import serve
+
+        with pytest.raises(Exit):
+            serve(host="localhost", port=8124, log_level="INFO")
+
+
+def test_serve_with_params() -> None:
+    """Test serve starts uvicorn when params provided."""
+    mock_tinytuya = MagicMock()
+    with patch.dict(sys.modules, {"tinytuya": mock_tinytuya}):
+        if "python.heater.controller" in sys.modules:
+            del sys.modules["python.heater.controller"]
+        if "python.heater.main" in sys.modules:
+            del sys.modules["python.heater.main"]
+        from python.heater.main import serve
+
+        with patch("python.heater.main.uvicorn.run") as mock_run:
+            serve(
+                host="localhost",
+                port=8124,
+                log_level="INFO",
+                device_id="abc",
+                device_ip="10.0.0.1",
+                local_key="key123",
+            )
+            mock_run.assert_called_once()
+
+
+def test_heater_off_route_failure() -> None:
+    """Test /off route raises HTTPException on failure."""
+    mock_tinytuya = MagicMock()
+    mock_device = MagicMock()
+    mock_device.set_value.side_effect = ConnectionError("fail")
+    mock_tinytuya.Device.return_value = mock_device
+
+    with patch.dict(sys.modules, {"tinytuya": mock_tinytuya}):
+        if "python.heater.controller" in sys.modules:
+            del sys.modules["python.heater.controller"]
+        if "python.heater.main" in sys.modules:
+            del sys.modules["python.heater.main"]
+        from python.heater.main import create_app
+        from python.heater.controller import HeaterController
+        from fastapi import HTTPException
+
+        config = DeviceConfig(device_id="abc", ip="10.0.0.1", local_key="key")
+        app = create_app(config)
+        app.state.controller = HeaterController(config)
+
+        for route in app.routes:
+            if hasattr(route, "path") and route.path == "/off":
+                with pytest.raises(HTTPException):
+                    route.endpoint()
+                break
+
+
+def test_heater_toggle_route_failure() -> None:
+    """Test /toggle route raises HTTPException on failure."""
+    mock_tinytuya = MagicMock()
+    mock_device = MagicMock()
+    # toggle calls status() first then set_value - make set_value fail
+    mock_device.status.return_value = {"dps": {"1": True}}
+    mock_device.set_value.side_effect = ConnectionError("fail")
+    mock_tinytuya.Device.return_value = mock_device
+
+    with patch.dict(sys.modules, {"tinytuya": mock_tinytuya}):
+        if "python.heater.controller" in sys.modules:
+            del sys.modules["python.heater.controller"]
+        if "python.heater.main" in sys.modules:
+            del sys.modules["python.heater.main"]
+        from python.heater.main import create_app
+        from python.heater.controller import HeaterController
+        from fastapi import HTTPException
+
+        config = DeviceConfig(device_id="abc", ip="10.0.0.1", local_key="key")
+        app = create_app(config)
+        app.state.controller = HeaterController(config)
+
+        for route in app.routes:
+            if hasattr(route, "path") and route.path == "/toggle":
+                with pytest.raises(HTTPException):
+                    route.endpoint()
+                break