validate non-GenericAlias attribute hints

Author: James Souter

src/fastcs/util.py

@@ -39,10 +39,18 @@ def validate_hinted_attributes(controller: BaseController):
     """
     for subcontroller in controller.sub_controllers.values():
         validate_hinted_attributes(subcontroller)
-    hints = get_type_hints(type(controller))
-    alias_hints = {k: v for k, v in hints.items() if isinstance(v, _GenericAlias)}
-    for name, hint in alias_hints.items():
-        attr_class = get_origin(hint)
+    hints = {
+        k: v
+        for k, v in get_type_hints(type(controller)).items()
+        if isinstance(v, _GenericAlias | type)
+    }
+    for name, hint in hints.items():
+        if isinstance(hint, type):
+            attr_class = hint
+            attr_dtype = None
+        else:
+            attr_class = get_origin(hint)
+            (attr_dtype,) = get_args(hint)
         if not issubclass(attr_class, Attribute):
             continue
 
@@ -52,16 +60,14 @@ def validate_hinted_attributes(controller: BaseController):
                 f"Controller `{controller.__class__.__name__}` failed to introspect "
                 f"hinted attribute `{name}` during initialisation"
             )
-
-        if type(attr) is not attr_class:
+        if attr_class not in [type(attr), Attribute]:
+            # skip validation if access mode not specified
             raise RuntimeError(
                 f"Controller '{controller.__class__.__name__}' introspection of hinted "
                 f"attribute '{name}' does not match defined access mode. "
                 f"Expected '{attr_class.__name__}', got '{type(attr).__name__}'."
             )
-
-        attr_dtype = get_args(hint)[0]
-        if attr.datatype.dtype != attr_dtype:
+        if attr_dtype not in [attr.datatype.dtype, None]:
             raise RuntimeError(
                 f"Controller '{controller.__class__.__name__}' introspection of hinted "
                 f"attribute '{name}' does not match defined datatype. "

tests/test_util.py

@@ -5,7 +5,7 @@
 from pvi.device import SignalR
 from pydantic import ValidationError
 
-from fastcs.attributes import AttrR, AttrRW
+from fastcs.attributes import Attribute, AttrR, AttrRW
 from fastcs.backend import Backend
 from fastcs.controller import Controller
 from fastcs.datatypes import Bool, Enum, Float, Int, String
@@ -138,6 +138,15 @@ class ControllerWrongEnumClass(Controller):
         "Expected 'MyEnum', got 'MyEnum2'."
     )
 
+    class ControllerUnspecifiedAccessMode(Controller):
+        hinted: Attribute[int]
+
+        async def initialise(self):
+            self.hinted = AttrR(Int())
+
+    # no assertion thrown
+    Backend(ControllerUnspecifiedAccessMode(), loop)
+
 
 def test_hinted_attributes_verified_on_subcontrollers():
     loop = asyncio.get_event_loop()
@@ -155,3 +164,25 @@ async def initialise(self):
 
     with pytest.raises(RuntimeError, match="failed to introspect hinted attribute"):
         Backend(TopController(), loop)
+
+
+def test_hinted_attribute_types_verified():
+    # test verification works with non-GenericAlias type hints
+    loop = asyncio.get_event_loop()
+
+    class ControllerAttrWrongAccessMode(Controller):
+        read_attr: AttrR
+
+        async def initialise(self):
+            self.read_attr = AttrRW(Int())
+
+    with pytest.raises(RuntimeError, match="does not match defined access mode"):
+        Backend(ControllerAttrWrongAccessMode(), loop)
+
+    class ControllerUnspecifiedAccessMode(Controller):
+        unspecified_access_mode: Attribute
+
+        async def initialise(self):
+            self.unspecified_access_mode = AttrRW(Int())
+
+    Backend(ControllerUnspecifiedAccessMode(), loop)