fix: Fix ClassVarTypeHint._copy_with_args()

Author: NiklasRosenstein

.changelog/_unreleased.toml

@@ -0,0 +1,5 @@
+[[entries]]
+id = "20ce9dbc-dcb5-432c-9a72-b0c085f70180"
+type = "fix"
+description = "Fix `ClassVarTypeHint._copy_with_args()`"
+author = "@NiklasRosenstein"

src/typeapi/typehint.py

@@ -538,3 +538,7 @@ def __init__(self, hint: object, source: "Any | None" = None) -> None:
                 self._args = (self.hint.__type__,)  # type: ignore[attr-defined]
             else:
                 self._args = ()
+
+    def _copy_with_args(self, args: Tuple[Any, ...]) -> TypeHint:
+        assert len(args) == 1, "a ClassVar type hint requires exactly one argument"
+        return ClassVarTypeHint(ClassVar[args[0]])

src/typeapi/typehint_test.py

@@ -602,3 +602,8 @@ def test__TypeHint__with_ClassVar() -> None:
     assert hint.hint == ClassVar[Union[int, str]]
     assert hint.args == (Union[int, str],)
     assert hint[0] == TypeHint(Union[int, str])
+
+
+def test__ClassVarTypeHint__copy_with_args() -> None:
+    hint = TypeHint(ClassVar[int])
+    assert hint._copy_with_args((str,)).hint == ClassVar[str]