fix: Handle partials as functions while inspecting

This doesn't solve the issue that `functools.partial` does not set the `__module__` attribute of the resulting partial to be the module of the wrapped function, which means that the inspector always treats partials as aliases (since it finds out they were defined in the `functools` module).

This issue cannot be fixed on our side, because special-casing partials to decide that they are always defined in the current module would not work for partials imported from elsewhere.

Therefore, devs *must* set the `__module__` attribute of partials themselves.

src/griffe/agents/nodes/_runtime.py

@@ -120,14 +120,14 @@ def kind(self) -> ObjectKind:
             return ObjectKind.BUILTIN_METHOD
         if self.is_coroutine:
             return ObjectKind.COROUTINE
-        if self.is_function:
-            return ObjectKind.FUNCTION
         if self.is_builtin_function:
             return ObjectKind.BUILTIN_FUNCTION
-        if self.is_property:
-            return ObjectKind.PROPERTY
         if self.is_method_descriptor:
             return ObjectKind.METHOD_DESCRIPTOR
+        if self.is_function:
+            return ObjectKind.FUNCTION
+        if self.is_property:
+            return ObjectKind.PROPERTY
         return ObjectKind.ATTRIBUTE
 
     @cached_property
@@ -152,7 +152,8 @@ def is_class(self) -> bool:
     @cached_property
     def is_function(self) -> bool:
         """Whether this node's object is a function."""
-        return inspect.isfunction(self.obj)
+        # `inspect.isfunction` returns `False` for partials.
+        return inspect.isfunction(self.obj) or (callable(self.obj) and not self.is_class)
 
     @cached_property
     def is_builtin_function(self) -> bool:

tests/test_inspector.py

@@ -139,3 +139,20 @@ def test_inspecting_objects_from_private_builtin_stdlib_moduless() -> None:
     ast = inspect("_ast")
     assert "Assign" in ast.members
     assert not ast["Assign"].is_alias
+
+
+def test_inspecting_partials_as_functions() -> None:
+    """Assert partials are correctly inspected as functions."""
+    with temporary_inspected_module(
+        """
+        from functools import partial
+        def func(a: int, b: int) -> int: pass
+        partial_func = partial(func, 1)
+        partial_func.__module__ = __name__
+        """,
+    ) as module:
+        partial_func = module["partial_func"]
+        assert partial_func.is_function
+        assert partial_func.parameters[0].name == "b"
+        assert partial_func.parameters[0].annotation.name == "int"
+        assert partial_func.returns.name == "int"