AreaNthSelector ignores "bad" Wires

AreaNthSelector.key raises ValueError if temporary face creation fails for a wire for any reason (non-planar, non-closed). That causes _NthSelector that it inherits to ignore such wires. Done so for consistency with RadiusNthSelector that ignores anything it can not get radius from.

cadquery/selectors.py

@@ -488,10 +488,12 @@ class AreaNthSelector(_NthSelector):
 
  Applicability:
  Faces, Shells, Solids - Shape.Area() is used to compute area
- planar Wires - a temporary face is created to compute area
+ closed planar Wires - a temporary face is created to compute area
 
- Among other things can be used to select one of 
- the nested coplanar wires or faces. 
+ Will ignore non-planar or non-closed wires.
+ 
+ Among other things can be used to select one of
+ the nested coplanar wires or faces.
 
  For example to create a fillet on a shank:
 
@@ -507,7 +509,7 @@ class AreaNthSelector(_NthSelector):
  )
 
  Or to create a lip on a case seam:
- 
+
  result = (
  cq.Workplane("XY")
  .rect(20, 20)
@@ -534,7 +536,12 @@ def key(self, obj: Shape) -> float:
  if isinstance(obj, (Face, Shell, Solid)):
  return obj.Area()
  elif isinstance(obj, Wire):
- return Face.makeFromWires(obj).Area()
+ try:
+ return Face.makeFromWires(obj).Area()
+ except Exception as ex:
+ raise ValueError(
+ f"Can not compute area of the Wire: {ex}. AreaNthSelector supports only closed planar Wires."
+ )
  else:
  raise ValueError(
  f"AreaNthSelector supports only Wires, Faces, Shells and Solids, not {type(obj).__name__}"

tests/test_selectors.py

@@ -826,7 +826,7 @@ def testAreaNthSelector_Edges(self):
  with self.assertRaises(IndexError):
  Workplane("XY").box(10, 10, 10).edges(selectors.AreaNthSelector(0))
 
- def testAreaNthSelector_Wires(self):
+ def testAreaNthSelector_NestedWires(self):
  """
  Tests key parts of case seam leap creation algorithm
  (see example 26)
@@ -899,6 +899,33 @@ def testAreaNthSelector_Wires(self):
  msg="Failed to select inner wire of 2 faces: wrong area",
  )
 
+ def testAreaNthSelector_NonplanarWire(self):
+ """
+ AreaNthSelector should raise ValueError when
+ used on non-planar wires so that they are ignored by
+ _NthSelector.
+
+ Non-planar wires in stack should not prevent selection of
+ planar wires.
+ """
+ wp = Workplane("XY").circle(10).extrude(50)
+
+ with self.assertRaises(IndexError):
+ wp.wires(selectors.AreaNthSelector(1))
+
+ cylinder_flat_ends = wp.wires(selectors.AreaNthSelector(0))
+ self.assertEqual(
+ len(cylinder_flat_ends.vals()),
+ 2,
+ msg="Failed to select cylinder flat end wires: wrong N wires",
+ )
+ self.assertTupleAlmostEquals(
+ [math.pi * 10 ** 2] * 2,
+ [Face.makeFromWires(wire).Area() for wire in cylinder_flat_ends.vals()],
+ 5,
+ msg="Failed to select cylinder flat end wires: wrong area",
+ )
+
  def testAreaNthSelector_Faces(self):
  """
  Selecting two faces of 10x20x30 box with intermediate area.