[ILibraryView / Pattern] flatten() should raise PatternError if asked to preserve ports from a repeated ref

masque/test/test_library.py

@@ -77,6 +77,20 @@ def test_library_flatten_preserves_ports_only_child() -> None:
     assert tuple(flat_parent.ports["P1"].offset) == (11.0, 12.0)
 
 
+def test_library_flatten_repeated_ref_with_ports_raises() -> None:
+    lib = Library()
+    child = Pattern(ports={"P1": Port((1, 2), 0)})
+    child.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+    lib["child"] = child
+
+    parent = Pattern()
+    parent.ref("child", repetition=Grid(a_vector=(10, 0), a_count=2))
+    lib["parent"] = parent
+
+    with pytest.raises(PatternError, match='Cannot flatten ports from repeated ref'):
+        lib.flatten("parent", flatten_ports=True)
+
+
 def test_lazy_library() -> None:
     lib = LazyLibrary()
     called = 0