feat: enhance _find_spec function and add nested module support

Author: fanck0605

src/awepatch/_module.py

@@ -99,7 +99,11 @@ def find_spec(
 
 
 def _find_spec(name: str) -> ModuleSpec | None:
-    """Find a module's spec."""
+    """Find a module's spec without importing it.
+
+    For nested modules like 'a.b.c', we need to find the parent's spec first
+    to get the search path, but we don't import the parent.
+    """
     if name in sys.modules:
         # The module is already imported, so we can skip the finders and just
         # return the spec from sys.modules.
@@ -111,13 +115,22 @@ def _find_spec(name: str) -> ModuleSpec | None:
 
         warnings.warn("sys.meta_path is empty", ImportWarning, stacklevel=2)
 
+    # For nested modules, we need to find the parent spec first
+    path = None
+    parent_name = name.rpartition(".")[0]
+    if parent_name:
+        parent_spec = _find_spec(parent_name)
+        if parent_spec is None:
+            return None
+        path = parent_spec.submodule_search_locations
+
     for finder in meta_path:
         try:
             find_spec = finder.find_spec
         except AttributeError:
             continue
         else:
-            spec = find_spec(name, None)
+            spec = find_spec(name, path)
             if spec is not None:
                 return spec
     else:

tests/__init__.py

@@ -6,18 +6,9 @@
 
 
 def test_module_patch_dataclass() -> None:
-    from tests.test_module import module_for_test
-
-    importlib.reload(module_for_test)
-
-    user = module_for_test.User(name="Alice", age=230)
-    assert user.name == "Alice"
-    assert user.age == 230
-    assert not hasattr(user, "gender")
-
     patcher = ModulePatcher()
     patcher.add_patch(
-        "tests.test_module.module_for_test",
+        "tests.test_module.nested.module_for_test",
         target="class User:",
         content=""" 
 @dataclass
@@ -29,7 +20,7 @@ class User:
         mode="replace",
     )
     patcher.add_patch(
-        "tests.test_module.module_for_test",
+        "tests.test_module.nested.module_for_test",
         target="def greet(user: User) -> str:",
         content=""" 
 def greet(user: User) -> str:
@@ -38,6 +29,8 @@ def greet(user: User) -> str:
         mode="replace",
     )
     patcher.apply()
+    from tests.test_module.nested import module_for_test
+
     importlib.reload(module_for_test)
     try:
         patched_user = module_for_test.User(name="Bob", age=25)
@@ -54,25 +47,18 @@ def greet(user: User) -> str:
 
 
 def test_module_patch_field() -> None:
-    from tests.test_module import module_for_test
-
-    importlib.reload(module_for_test)
-
-    user = module_for_test.User(name="Alice", age=230)
-    assert user.name == "Alice"
-    assert user.age == 230
-    assert not hasattr(user, "gender")
-
     patcher = ModulePatcher()
     patcher.add_patch(
-        "tests.test_module.module_for_test",
+        "tests.test_module.nested.module_for_test",
         target=("class User:", "age: int"),
         content=""" 
 gender: str = "unspecified"
 """,
         mode="after",
     )
     patcher.apply()
+    from tests.test_module.nested import module_for_test
+
     importlib.reload(module_for_test)
     try:
         importlib.reload(module_for_test)