type modernization

tests/test_dagset.py

@@ -39,6 +39,10 @@ class TestDAGSetInit:
         s = DAGSetView(None)
         assert len(s) == 0
 
+    def test_from_scalar(self) -> None:
+        s = DAGSetView[int](2)
+        assert set(s) == {2}
+
 
 class TestDAGSetBasicOps:
     """Test basic set operations."""
@@ -169,6 +173,20 @@ class TestDAGSetCallbacks:
 class TestDAGSetInPlaceOperators:
     """Test in-place set operators."""
 
+    def test_scalar_operators_preserve_instance(self) -> None:
+        class IntSetView(DAGSetView[int]):
+            pass
+
+        view = IntSetView({1, 2})
+        original = view
+        view += 3
+        view |= 4
+        view -= 1
+        view &= 2
+        view ^= 5
+        assert view is original
+        assert set(view) == {2, 5}
+
     class TestIOR:
         def test_set(self) -> None:
             s = DAGSetView({"foo", 2})