feat(hot-reload): Implement HotReloader.reload and reload_all

src/hot_reloader.py

@@ -29,4 +29,39 @@ class HotReloader:
     @classmethod
     def restore_state(cls, app: Any, state: dict[str, Any]) -> None:
         for key, value in state.items():
-            setattr(app, key, value)
+            setattr(app, key, value)
+
+    @classmethod
+    def reload(cls, module_name: str, app: Any) -> bool:
+        if module_name not in cls.HOT_MODULES:
+            cls.last_error = f"Module {module_name} not registered"
+            cls.is_error_state = True
+            return False
+
+        hm = cls.HOT_MODULES[module_name]
+        state = cls.capture_state(app, hm.state_keys)
+
+        try:
+            import importlib
+            import sys
+            if module_name in sys.modules:
+                old_module = sys.modules[module_name]
+                importlib.reload(old_module)
+            else:
+                importlib.import_module(module_name)
+            cls.last_error = None
+            cls.is_error_state = False
+            return True
+        except Exception:
+            cls.restore_state(app, state)
+            cls.last_error = traceback.format_exc()
+            cls.is_error_state = True
+            return False
+
+    @classmethod
+    def reload_all(cls, app: Any) -> bool:
+        success = True
+        for name in cls.HOT_MODULES:
+            if not cls.reload(name, app):
+                success = False
+        return success

tests/test_hot_reloader.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 import pytest
 from src.hot_reloader import HotModule, HotReloader
+from unittest.mock import MagicMock, patch
+import sys
+import types
 
 def test_hot_module_dataclass_fields():
     hm = HotModule(
@@ -32,4 +35,66 @@ def test_hot_reloader_is_error_state():
     HotReloader.HOT_MODULES.clear()
     HotReloader.last_error = None
     HotReloader.is_error_state = False
-    assert HotReloader.is_error_state is False
+    assert HotReloader.is_error_state is False
+
+def test_reload_unknown_module_returns_false():
+    HotReloader.HOT_MODULES.clear()
+    HotReloader.register(HotModule(name="nonexistent_mod", file_path="/nonexistent.py", state_keys=[], delegation_targets=[]))
+    app = MagicMock()
+    result = HotReloader.reload("nonexistent_mod", app)
+    assert result is False
+    assert HotReloader.is_error_state is True
+    assert HotReloader.last_error is not None
+
+def test_reload_success_clears_error_state():
+    HotReloader.HOT_MODULES.clear()
+    test_mod = types.ModuleType("src._test_reload_mod_src")
+    sys.modules["src._test_reload_mod_src"] = test_mod
+    HotReloader.register(HotModule(name="src._test_reload_mod_src", file_path="/fake.py", state_keys=[], delegation_targets=[]))
+    app = MagicMock()
+    HotReloader.is_error_state = True
+    HotReloader.last_error = "previous error"
+    with patch("importlib.reload", return_value=test_mod):
+        result = HotReloader.reload("src._test_reload_mod_src", app)
+    assert result is True
+    assert HotReloader.is_error_state is False
+    assert HotReloader.last_error is None
+    del sys.modules["src._test_reload_mod_src"]
+
+def test_reload_captures_and_restores_state_on_failure():
+    HotReloader.HOT_MODULES.clear()
+    HotReloader.register(HotModule(name="bad_mod", file_path="/bad.py", state_keys=["_test_attr"], delegation_targets=[]))
+    app = MagicMock()
+    app._test_attr = "preserved_value"
+    result = HotReloader.reload("bad_mod", app)
+    assert result is False
+    assert HotReloader.is_error_state is True
+    assert app._test_attr == "preserved_value"
+
+def test_reload_all_success():
+    HotReloader.HOT_MODULES.clear()
+    mod1 = types.ModuleType("hr_test_mod1")
+    mod2 = types.ModuleType("hr_test_mod2")
+    sys.modules["hr_test_mod1"] = mod1
+    sys.modules["hr_test_mod2"] = mod2
+    HotReloader.register(HotModule(name="hr_test_mod1", file_path="/fake1.py", state_keys=[], delegation_targets=[]))
+    HotReloader.register(HotModule(name="hr_test_mod2", file_path="/fake2.py", state_keys=[], delegation_targets=[]))
+    app = MagicMock()
+    with patch("importlib.reload", return_value=mod1):
+        result = HotReloader.reload_all(app)
+    assert result is True
+    assert HotReloader.is_error_state is False
+    del sys.modules["hr_test_mod1"]
+    del sys.modules["hr_test_mod2"]
+
+def test_reload_all_partial_failure():
+    HotReloader.HOT_MODULES.clear()
+    mod1 = types.ModuleType("hr_test_mod1")
+    sys.modules["hr_test_mod1"] = mod1
+    HotReloader.register(HotModule(name="hr_test_mod1", file_path="/fake1.py", state_keys=[], delegation_targets=[]))
+    HotReloader.register(HotModule(name="hr_nonexistent", file_path="/nonexistent.py", state_keys=[], delegation_targets=[]))
+    app = MagicMock()
+    result = HotReloader.reload_all(app)
+    assert result is False
+    assert HotReloader.is_error_state is True
+    del sys.modules["hr_test_mod1"]