fix: Don't return class variables as parameters of dataclasses

PR-253: #253

Author: has2k1

src/griffe/extensions/dataclasses.py

@@ -80,8 +80,18 @@ def _dataclass_parameters(class_: Class) -> list[Parameter]:
         if member.is_attribute:
             member = cast(Attribute, member)
 
-            # Exclude @property and @cached_property attributes
-            if "property" in member.labels:
+            # Attributes that have labels for these characteristics are
+            # not class parameters:
+            #   - @property
+            #   - @cached_property
+            #   - ClassVar annotation
+            if "property" in member.labels or (
+                # TODO: It is better to explicitly check for ClassVar, but
+                # Visitor.handle_attribute unwraps it from the annotation.
+                # Maybe create internal_labels and store classvar in there.
+                "class-attribute" in member.labels
+                and "instance-attribute" not in member.labels
+            ):
                 continue
 
             # Start of keyword-only parameters.

tests/test_dataclasses.py

@@ -91,17 +91,23 @@ def test_alias_proxies() -> None:
                 assert name in alias_members
 
 
-def test_dataclass_properties() -> None:
-    """Don't return properties as parameters of dataclasses."""
+def test_dataclass_properties_and_class_variables() -> None:
+    """Don't return properties or class variables as parameters of dataclasses."""
     code = """
         from dataclasses import dataclass
         from functools import cached_property
+        from typing import ClassVar
 
         @dataclass
         class Point:
             x: float
             y: float
 
+            # These definitions create class variables
+            r: ClassVar[float]
+            s: float = 3
+            t: ClassVar[float] = 3
+
             @property
             def a(self):
                 return 0
@@ -112,7 +118,7 @@ def b(self):
     """
     with temporary_visited_package("package", {"__init__.py": code}) as module:
         params = module["Point"].parameters
-        assert [p.name for p in params] == ["self", "x", "y"]
+        assert [p.name for p in params] == ["self", "x", "y", "s"]
 
 
 @pytest.mark.parametrize(