Fix test_property tests

This caught a few errors in my rearrangement - most notably that only DataProperties were getting added to the HTTP API.

I've fixed things so all properties now appear on HTTP, and improved model
generation so it has helpful errors and
works for both data and functional properties.

I also removed the numpy mypy plugin because the warning got annoying.

Author: rwb27

pyproject.toml

@@ -93,7 +93,7 @@ preview = true
 "docs/*" = ["D", "DOC"]
 
 [tool.mypy]
-plugins = ["pydantic.mypy", "numpy.typing.mypy_plugin"]
+plugins = ["pydantic.mypy"]
 
 [tool.flake8]
 extend-ignore = [

src/labthings_fastapi/base_descriptor.py

@@ -17,11 +17,31 @@
 """The value returned by the descriptor, when called on an instance."""
 
 
-class NameNotSetError(AttributeError):
-    """Descriptor name is not yet available.
+class DescriptorNotAddedToClassError(RuntimeError):
+    """Descriptor has not yet been added to a class.
 
-    This error is raised if the name of an affordance is accessed
-    before ``__set_name__`` has been called on the descriptor.
+    This error is raised if certain properties of descriptors are accessed
+    before ``__set_name__`` has been called on the descriptor.  ``__set_name``
+    is part of the descriptor protocol, and is called when a class is defined
+    to notify the descriptor of its name and owning class.
+
+    If you see this error, it often means that a descriptor has been instantiated
+    but not attached to a class, for example:
+
+    .. code-block:: python
+
+        import labthings as lt
+
+
+        class Test(lt.Thing):
+            myprop: int = lt.property(0)  # This is OK
+
+
+        orphaned_prop: int = lt.property(0)  # Not OK
+
+        Test.myprop.model  # Evaluates to a pydantic model
+
+        orphaned_prop.model  # Raises this exception
     """
 
 
@@ -44,6 +64,9 @@ def __init__(self) -> None:
         # We set the instance __doc__ to None so the descriptor class docstring
         # doesn't get picked up by OpenAPI/Thing Description.
         self.__doc__ = None
+        # We explicitly check when __set_name__ is called, so we can raise helpful
+        # errors
+        self._set_name_called: bool = False
 
     def __set_name__(self, owner: type[Thing], name: str) -> None:
         r"""Take note of the name to which the descriptor is assigned.
@@ -58,6 +81,21 @@ def __set_name__(self, owner: type[Thing], name: str) -> None:
         # Remember the name to which we're assigned. Accessed by the read only
         # property ``name``.
         self._name = name
+        self._set_name_called = True
+
+    def assert_set_name_called(self):
+        """Raise an exception if ``__set_name__`` has not yet been called.
+
+        :raises DescriptorNotAddedToClassError: if ``__set_name__`` has not yet
+            been called.
+        """
+        if not self._set_name_called:
+            raise DescriptorNotAddedToClassError(
+                f"{self.__class__.__name__} must be assigned to an attribute of "
+                "a class, as part of the class definition. This exception is "
+                "raised because `__set_name__` has not yet been called, which "
+                "usually means it was not instantiated as a class attribute."
+            )
 
     @property
     def name(self) -> str:
@@ -74,8 +112,10 @@ def name(self) -> str:
         :raises NameNotSetError: if it is accessed before the descriptor
             has been notified of its name.
         """
-        if self._name is None:
-            raise NameNotSetError
+        self.assert_set_name_called()
+        assert self._name is not None
+        # The assert statement is mostly for typing: if assert_set_name_called
+        # doesn't raise an error, self._name has been set.
         return self._name
 
     @property

src/labthings_fastapi/exceptions.py

@@ -21,7 +21,7 @@ def __init__(self, message: str | None = None):
 
         :param message: the optional message.
         """
-        # type: ignore[call-arg] is used here because mypy can't know
+        # We ignore call-arg within this function because mypy can't know
         # that this is a mixin, and super() will be an exception (which does
         # accept a string argument to `__init__`).
         doc = inspect.cleandoc(self.__doc__) if self.__doc__ else None

src/labthings_fastapi/thing.py

@@ -21,7 +21,7 @@
 
 from pydantic import BaseModel
 
-from .thing_property import BaseProperty, ThingSetting
+from .thing_property import DataProperty, ThingSetting
 from .descriptors import ActionDescriptor
 from .thing_description._model import ThingDescription, NoSecurityScheme
 from .utilities import class_attributes
@@ -348,7 +348,7 @@ def observe_property(self, property_name: str, stream: ObjectSendStream) -> None
         :raise KeyError: if the requested name is not defined on this Thing.
         """
         prop = getattr(self.__class__, property_name)
-        if not isinstance(prop, BaseProperty):
+        if not isinstance(prop, DataProperty):
             raise KeyError(f"{property_name} is not a LabThings Property")
         prop._observers_set(self).add(stream)