Mixin3D.shell: allow faceList=None

Author: marcus7070

cadquery/occ_impl/shapes.py

@@ -2351,7 +2351,7 @@ def chamfer(
 
     def shell(
         self: Any,
-        faceList: Iterable[Face],
+        faceList: Optional[Iterable[Face]],
         thickness: float,
         tolerance: float = 0.0001,
         kind: Literal["arc", "intersection"] = "arc",
@@ -2375,8 +2375,9 @@ def shell(
         occ_faces_list = TopTools_ListOfShape()
         shell_builder = BRepOffsetAPI_MakeThickSolid()
 
-        for f in faceList:
-            occ_faces_list.Append(f.wrapped)
+        if faceList:
+            for f in faceList:
+                occ_faces_list.Append(f.wrapped)
 
         shell_builder.MakeThickSolidByJoin(
             self.wrapped,

tests/test_cadquery.py

@@ -2290,6 +2290,14 @@ def testClosedShell(self):
         s3 = Workplane().polyline(pts).close().extrude(1).shell(-0.05)
         self.assertTrue(s3.val().isValid())
 
+        s4_shape = Workplane("XY").box(2, 2, 2).val()
+        # test that None and empty list both work and are equivalent
+        s4_shell_1 = s4_shape.shell(faceList=None, thickness=-0.1)
+        s4_shell_2 = s4_shape.shell(faceList=[], thickness=-0.1)
+        # this should be the same as the first shape
+        self.assertEqual(len(s4_shell_1.Faces()), s1.faces().size())
+        self.assertEqual(len(s4_shell_2.Faces()), s1.faces().size())
+
     def testOpenCornerShell(self):
         s = Workplane("XY").box(1, 1, 1)
         s1 = s.faces("+Z")