Refining code and adding tests

src/build123d/__init__.py

@@ -55,13 +55,13 @@ __all__ = [
     "Intrinsic",
     "Keep",
     "Kind",
-    "LengthConstraint",
+    "Sagitta",
     "LengthMode",
     "MeshType",
     "Mode",
     "NumberDisplay",
     "PageSize",
-    "PositionConstraint",
+    "Tangency",
     "PositionMode",
     "PrecisionMode",
     "Select",

src/build123d/build_enums.py

@@ -254,8 +254,8 @@ class FontStyle(Enum):
         return f"<{self.__class__.__name__}.{self.name}>"
 
 
-class LengthConstraint(Enum):
-    """Length Constraint for sagitta selection"""
+class Sagitta(Enum):
+    """Sagitta selection"""
 
     SHORT = 0
     LONG = -1
@@ -320,8 +320,8 @@ class PageSize(Enum):
         return f"<{self.__class__.__name__}.{self.name}>"
 
 
-class PositionConstraint(Enum):
-    """Position Constraint for edge selection"""
+class Tangency(Enum):
+    """Tangency constraint for solvers edge selection"""
 
     UNQUALIFIED = GccEnt_unqualified
     ENCLOSING = GccEnt_enclosing

src/build123d/topology/constrained_lines.py

@@ -70,7 +70,7 @@ from OCP.gp import (
 )
 from OCP.TopoDS import TopoDS_Edge
 
-from build123d.build_enums import LengthConstraint, PositionConstraint
+from build123d.build_enums import Sagitta, Tangency
 from build123d.geometry import TOLERANCE, Vector, VectorLike
 from .zero_d import Vertex
 from .shape_core import ShapeList
@@ -113,7 +113,7 @@ def _forward_delta(u1: float, u2: float, first: float, period: float) -> float:
 # Core helpers
 # ---------------------------
 def _edge_to_qualified_2d(
-    edge: TopoDS_Edge, position_constaint: PositionConstraint
+    edge: TopoDS_Edge, position_constaint: Tangency
 ) -> tuple[Geom2dGcc_QualifiedCurve, Geom2d_Curve, float, float]:
     """Convert a TopoDS_Edge into 2d curve & extract properties"""
 
@@ -153,9 +153,7 @@ def _param_in_trim(u: float, first: float, last: float, h2d: Geom2d_Curve) -> bo
     return (u >= first - TOLERANCE) and (u <= last + TOLERANCE)
 
 
-def _as_gcc_arg(
-    obj: Edge | Vertex | VectorLike, constaint: PositionConstraint
-) -> tuple[
+def _as_gcc_arg(obj: Edge | Vertex | VectorLike, constaint: Tangency) -> tuple[
     Geom2dGcc_QualifiedCurve | Geom2d_CartesianPoint,
     Geom2d_Curve | None,
     float | None,
@@ -229,9 +227,9 @@ def _qstr(q) -> str:
 
 
 def _make_2tan_rad_arcs(
-    *tangencies: tuple[Edge, PositionConstraint] | Edge | Vector,  # 2
+    *tangencies: tuple[Edge, Tangency] | Edge | Vector,  # 2
     radius: float,
-    sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+    sagitta: Sagitta = Sagitta.SHORT,
     edge_factory: Callable[[TopoDS_Edge], TWrap],
 ) -> list[Edge]:
     """
@@ -259,8 +257,7 @@ def _make_2tan_rad_arcs(
 
     # Unpack optional per-edge qualifiers (default UNQUALIFIED)
     tangent_tuples = [
-        t if isinstance(t, tuple) else (t, PositionConstraint.UNQUALIFIED)
-        for t in tangencies
+        t if isinstance(t, tuple) else (t, Tangency.UNQUALIFIED) for t in tangencies
     ]
 
     # Build inputs for GCC
@@ -310,21 +307,21 @@ def _make_2tan_rad_arcs(
         # )
 
         # Build BOTH sagitta arcs and select by LengthConstraint
-        if sagitta_constraint == LengthConstraint.BOTH:
+        if sagitta == Sagitta.BOTH:
             solutions.extend(_two_arc_edges_from_params(circ, u_circ1, u_circ2))
         else:
             arcs = _two_arc_edges_from_params(circ, u_circ1, u_circ2)
             arcs = sorted(
                 arcs, key=lambda e: GCPnts_AbscissaPoint.Length_s(BRepAdaptor_Curve(e))
             )
-            solutions.append(arcs[sagitta_constraint.value])
+            solutions.append(arcs[sagitta.value])
     return ShapeList([edge_factory(e) for e in solutions])
 
 
 def _make_2tan_on_arcs(
-    *tangencies: tuple[Edge, PositionConstraint] | Edge | Vector,  # 2
+    *tangencies: tuple[Edge, Tangency] | Edge | Vector,  # 2
     center_on: Edge,
-    sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+    sagitta: Sagitta = Sagitta.SHORT,
     edge_factory: Callable[[TopoDS_Edge], TWrap],
 ) -> ShapeList[Edge]:
     """
@@ -338,8 +335,7 @@ def _make_2tan_on_arcs(
 
     # Unpack optional per-edge qualifiers (default UNQUALIFIED)
     tangent_tuples = [
-        t if isinstance(t, tuple) else (t, PositionConstraint.UNQUALIFIED)
-        for t in tangencies
+        t if isinstance(t, tuple) else (t, Tangency.UNQUALIFIED) for t in tangencies
     ]
 
     # Build inputs for GCC
@@ -351,7 +347,7 @@ def _make_2tan_on_arcs(
 
     # Build center locus ("On") input
     _, h_on2d, e_first[2], e_last[2], adapt_on = _edge_to_qualified_2d(
-        center_on.wrapped, PositionConstraint.UNQUALIFIED
+        center_on.wrapped, Tangency.UNQUALIFIED
     )
     is_edge[2] = True
 
@@ -409,7 +405,7 @@ def _make_2tan_on_arcs(
             continue
 
         # Build sagitta arc(s) and select by LengthConstraint
-        if sagitta_constraint == LengthConstraint.BOTH:
+        if sagitta == Sagitta.BOTH:
             solutions.extend(_two_arc_edges_from_params(circ, u_circ1, u_circ2))
         else:
             arcs = _two_arc_edges_from_params(circ, u_circ1, u_circ2)
@@ -418,14 +414,14 @@ def _make_2tan_on_arcs(
             arcs = sorted(
                 arcs, key=lambda e: GCPnts_AbscissaPoint.Length_s(BRepAdaptor_Curve(e))
             )
-            solutions.append(arcs[sagitta_constraint.value])
+            solutions.append(arcs[sagitta.value])
 
     return ShapeList([edge_factory(e) for e in solutions])
 
 
 def _make_3tan_arcs(
-    *tangencies: tuple[Edge, PositionConstraint] | Edge | Vector,  # 3
-    sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+    *tangencies: tuple[Edge, Tangency] | Edge | Vector,  # 3
+    sagitta: Sagitta = Sagitta.SHORT,
     edge_factory: Callable[[TopoDS_Edge], TWrap],
 ) -> ShapeList[Edge]:
     """
@@ -433,14 +429,13 @@ def _make_3tan_arcs(
 
     The circle is determined by the three tangency constraints; the returned arc(s)
     are trimmed between the two tangency points corresponding to `tangencies[0]` and
-    `tangencies[1]`. Use `sagitta_constraint` to select the shorter/longer (or both) arc.
+    `tangencies[1]`. Use `sagitta` to select the shorter/longer (or both) arc.
     Inputs must be representable on Plane.XY.
     """
 
     # Unpack optional per-edge qualifiers (default UNQUALIFIED)
     tangent_tuples = [
-        t if isinstance(t, tuple) else (t, PositionConstraint.UNQUALIFIED)
-        for t in tangencies
+        t if isinstance(t, tuple) else (t, Tangency.UNQUALIFIED) for t in tangencies
     ]
 
     # Build inputs for GCC
@@ -491,7 +486,7 @@ def _make_3tan_arcs(
             continue
 
         # Build arc(s) between u_circ1 and u_circ2 per LengthConstraint
-        if sagitta_constraint == LengthConstraint.BOTH:
+        if sagitta == Sagitta.BOTH:
             out_topos.extend(_two_arc_edges_from_params(circ, u_circ1, u_circ2))
         else:
             arcs = _two_arc_edges_from_params(circ, u_circ1, u_circ2)
@@ -501,13 +496,13 @@ def _make_3tan_arcs(
                 arcs,
                 key=lambda e: GCPnts_AbscissaPoint.Length_s(BRepAdaptor_Curve(e)),
             )
-            out_topos.append(arcs[sagitta_constraint.value])
+            out_topos.append(arcs[sagitta.value])
 
     return ShapeList([edge_factory(e) for e in out_topos])
 
 
 def _make_tan_cen_arcs(
-    tangency: tuple[Edge, PositionConstraint] | Edge | Vector,
+    tangency: tuple[Edge, Tangency] | Edge | Vector,
     *,
     center: VectorLike | Vertex,
     edge_factory: Callable[[TopoDS_Edge], TWrap],
@@ -529,7 +524,7 @@ def _make_tan_cen_arcs(
     if isinstance(tangency, tuple):
         object_one, obj1_qual = tangency
     else:
-        object_one, obj1_qual = tangency, PositionConstraint.UNQUALIFIED
+        object_one, obj1_qual = tangency, Tangency.UNQUALIFIED
 
     # ---------------------------
     # Build fixed center (gp_Pnt2d)
@@ -590,7 +585,7 @@ def _make_tan_cen_arcs(
 
 
 def _make_tan_on_rad_arcs(
-    tangency: tuple[Edge, PositionConstraint] | Edge | Vector,
+    tangency: tuple[Edge, Tangency] | Edge | Vector,
     *,
     center_on: Edge,
     radius: float,
@@ -615,7 +610,7 @@ def _make_tan_on_rad_arcs(
     if isinstance(tangency, tuple):
         object_one, obj1_qual = tangency
     else:
-        object_one, obj1_qual = tangency, PositionConstraint.UNQUALIFIED
+        object_one, obj1_qual = tangency, Tangency.UNQUALIFIED
 
     # --- build tangency input (point/edge) ---
     q_o1, h_e1, e1_first, e1_last, is_edge1 = _as_gcc_arg(object_one, obj1_qual)
@@ -627,7 +622,7 @@ def _make_tan_on_rad_arcs(
 
     # Project the center locus Edge to 2D (XY)
     _, h_on2d, on_first, on_last, adapt_on = _edge_to_qualified_2d(
-        on_obj.wrapped, PositionConstraint.UNQUALIFIED
+        on_obj.wrapped, Tangency.UNQUALIFIED
     )
     gcc = Geom2dGcc_Circ2dTanOnRad(q_o1, adapt_on, radius, TOLERANCE)
 

src/build123d/topology/one_d.py

@@ -198,8 +198,8 @@ from build123d.build_enums import (
     GeomType,
     Keep,
     Kind,
-    LengthConstraint,
-    PositionConstraint,
+    Sagitta,
+    Tangency,
     PositionMode,
     Side,
 )
@@ -1588,11 +1588,11 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     @classmethod
     def make_constrained_arcs(
         cls,
-        tangency_one: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
-        tangency_two: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
+        tangency_one: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
+        tangency_two: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
         *,
         radius: float,
-        sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+        sagitta: Sagitta = Sagitta.SHORT,
     ) -> ShapeList[Edge]:
         """
         Create all planar circular arcs of a given radius that are tangent/contacting
@@ -1602,7 +1602,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
             tangency_two (tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike):
                 Geometric entities to be contacted/touched by the circle(s)
             radius (float): arc radius
-            sagitta_constraint (LengthConstraint, optional): returned arc selector
+            sagitta (LengthConstraint, optional): returned arc selector
                 (i.e. either the short, long or both arcs). Defaults to
                 LengthConstraint.SHORT.
 
@@ -1614,11 +1614,11 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     @classmethod
     def make_constrained_arcs(
         cls,
-        tangency_one: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
-        tangency_two: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
+        tangency_one: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
+        tangency_two: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
         *,
         center_on: Edge,
-        sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+        sagitta: Sagitta = Sagitta.SHORT,
     ) -> ShapeList[Edge]:
         """
         Create all planar circular arcs whose circle is tangent to two objects and whose
@@ -1629,7 +1629,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
             tangency_two (tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike):
                 Geometric entities to be contacted/touched by the circle(s)
             center_on (Edge): center must lie on this edge
-            sagitta_constraint (LengthConstraint, optional): returned arc selector
+            sagitta (LengthConstraint, optional): returned arc selector
                 (i.e. either the short, long or both arcs). Defaults to
                 LengthConstraint.SHORT.
 
@@ -1641,11 +1641,11 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     @classmethod
     def make_constrained_arcs(
         cls,
-        tangency_one: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
-        tangency_two: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
-        tangency_three: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
+        tangency_one: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
+        tangency_two: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
+        tangency_three: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
         *,
-        sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+        sagitta: Sagitta = Sagitta.SHORT,
     ) -> ShapeList[Edge]:
         """
         Create planar circular arc(s) on XY tangent to three provided objects.
@@ -1655,7 +1655,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
             tangency_two (tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike):
             tangency_three (tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike):
                 Geometric entities to be contacted/touched by the circle(s)
-            sagitta_constraint (LengthConstraint, optional): returned arc selector
+            sagitta (LengthConstraint, optional): returned arc selector
                 (i.e. either the short, long or both arcs). Defaults to
                 LengthConstraint.SHORT.
 
@@ -1667,7 +1667,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     @classmethod
     def make_constrained_arcs(
         cls,
-        tangency_one: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
+        tangency_one: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
         *,
         center: VectorLike,
     ) -> ShapeList[Edge]:
@@ -1689,7 +1689,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     @classmethod
     def make_constrained_arcs(
         cls,
-        tangency_one: tuple[Edge, PositionConstraint] | Edge | Vertex | VectorLike,
+        tangency_one: tuple[Edge, Tangency] | Edge | Vertex | VectorLike,
         *,
         radius: float,
         center_on: Edge,
@@ -1706,7 +1706,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
                 Geometric entity to be contacted/touched by the circle(s)
             radius (float): arc radius
             center_on (Edge): center must lie on this edge
-            sagitta_constraint (LengthConstraint, optional): returned arc selector
+            sagitta (LengthConstraint, optional): returned arc selector
                 (i.e. either the short, long or both arcs). Defaults to
                 LengthConstraint.SHORT.
 
@@ -1718,7 +1718,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
     def make_constrained_arcs(
         cls,
         *args,
-        sagitta_constraint: LengthConstraint = LengthConstraint.SHORT,
+        sagitta: Sagitta = Sagitta.SHORT,
         **kwargs,
     ) -> ShapeList[Edge]:
 
@@ -1738,22 +1738,22 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
         if kwargs:
             raise TypeError(f"Unexpected argument(s): {', '.join(kwargs.keys())}")
 
-        tangencies_raw = [
+        tangency_args = [
             t for t in (tangency_one, tangency_two, tangency_three) if t is not None
         ]
         tangencies = []
-        for tangency_raw in tangencies_raw:
-            if (
-                isinstance(tangency_raw, tuple)
-                and not isinstance(tangency_raw[0], Edge)
-            ) or not isinstance(tangency_raw, Edge):
+        for tangency_arg in tangency_args:
+            if isinstance(tangency_arg, Edge):
+                tangencies.append(tangency_arg)
+                continue
+            if isinstance(tangency_arg, tuple) and isinstance(tangency_arg[0], Edge):
+                tangencies.append(tangency_arg)
+                continue
+            # if not Edges or constrained Edges convert to Vectors
             try:
-                    tangency = Vector(tangency_raw)
-                except:
-                    raise TypeError("Invalid tangency")
-            else:
-                tangency = tangency_raw
-            tangencies.append(tangency)
+                tangencies.append(Vector(tangency_arg))
+            except Exception as exc:
+                raise TypeError(f"Invalid tangency: {tangency_arg!r}") from exc
 
         # Sort the tangency inputs so points are always last
         tangent_tuples = [t if isinstance(t, tuple) else (t, None) for t in tangencies]
@@ -1780,7 +1780,7 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
             return _make_2tan_rad_arcs(
                 *tangencies,
                 radius=radius,
-                sagitta_constraint=sagitta_constraint,
+                sagitta=sagitta,
                 edge_factory=cls,
             )
         if (
@@ -1792,13 +1792,11 @@ class Edge(Mixin1D, Shape[TopoDS_Edge]):
             return _make_2tan_on_arcs(
                 *tangencies,
                 center_on=center_on,
-                sagitta_constraint=sagitta_constraint,
+                sagitta=sagitta,
                 edge_factory=cls,
             )
         if tan_count == 3 and radius is None and center is None and center_on is None:
-            return _make_3tan_arcs(
-                *tangencies, sagitta_constraint=sagitta_constraint, edge_factory=cls
-            )
+            return _make_3tan_arcs(*tangencies, sagitta=sagitta, edge_factory=cls)
         if (
             tan_count == 1
             and center is not None

tests/test_direct_api/test_constrained_arcs.py

@@ -35,11 +35,12 @@ from build123d.objects_curve import (
     IntersectingLine,
     ThreePointArc,
 )
-from build123d.objects_sketch import Rectangle
-from build123d.topology import Edge, Solid, Vertex
-from build123d.geometry import Axis, Vector
-from build123d.build_enums import PositionConstraint, LengthConstraint, LengthMode
-
+from build123d.topology import Edge, Solid, Vertex, Wire, topo_explore_common_vertex
+from build123d.geometry import Axis, Vector, TOLERANCE
+from build123d.build_enums import Tangency, Sagitta, LengthMode
+from OCP.BRep import BRep_Tool
+from OCP.GeomAbs import GeomAbs_C1
+from OCP.LocalAnalysis import LocalAnalysis_CurveContinuity
 
 radius = 0.5
 e1 = Line((-2, 0), (2, 0))
@@ -51,13 +52,13 @@ e1.color = "Grey"
 e2.color = "Red"
 
 
-def test_constrained_arcs_0():
+def test_constrained_arcs_arg_processing():
     """Test input error handling"""
     with pytest.raises(TypeError):
         Edge.make_constrained_arcs(Solid.make_box(1, 1, 1), (1, 0), radius=0.5)
     with pytest.raises(TypeError):
         Edge.make_constrained_arcs(
-            (Vector(0, 0), PositionConstraint.UNQUALIFIED), (1, 0), radius=0.5
+            (Vector(0, 0), Tangency.UNQUALIFIED), (1, 0), radius=0.5
         )
     with pytest.raises(TypeError):
         Edge.make_constrained_arcs(pnt1=(1, 1, 1), pnt2=(1, 0), radius=0.5)
@@ -69,24 +70,26 @@ def test_constrained_arcs_0():
         Edge.make_constrained_arcs((0, 0), (0, 0.5), radius=-0.5)
 
 
-def test_constrained_arcs_1():
+def test_tan2_rad_arcs_1():
     """2 edges & radius"""
     e1 = Line((-2, 0), (2, 0))
     e2 = Line((0, -2), (0, 2))
 
     tan2_rad_edges = Edge.make_constrained_arcs(
-        e1,
-        e2,
-        radius=0.5,
-        sagitta_constraint=LengthConstraint.BOTH,
+        e1, e2, radius=0.5, sagitta=Sagitta.BOTH
     )
     assert len(tan2_rad_edges) == 8
 
     tan2_rad_edges = Edge.make_constrained_arcs(e1, e2, radius=0.5)
     assert len(tan2_rad_edges) == 4
 
+    tan2_rad_edges = Edge.make_constrained_arcs(
+        (e1, Tangency.UNQUALIFIED), (e2, Tangency.UNQUALIFIED), radius=0.5
+    )
+    assert len(tan2_rad_edges) == 4
 
-def test_constrained_arcs_2():
+
+def test_tan2_rad_arcs_2():
     """2 edges & radius"""
     e1 = CenterArc((0, 0), 1, 0, 90)
     e2 = Line((1, 0), (2, 0))
@@ -95,7 +98,7 @@ def test_constrained_arcs_2():
     assert len(tan2_rad_edges) == 1
 
 
-def test_constrained_arcs_3():
+def test_tan2_rad_arcs_3():
     """2 points & radius"""
     tan2_rad_edges = Edge.make_constrained_arcs((0, 0), (0, 0.5), radius=0.5)
     assert len(tan2_rad_edges) == 2
@@ -111,129 +114,98 @@ def test_constrained_arcs_3():
     assert len(tan2_rad_edges) == 2
 
 
-#     tan2_rad_edges = Edge.make_constrained_arcs(
-#         (e1, PositionConstraint.OUTSIDE),
-#         (e2, PositionConstraint.UNQUALIFIED),
-#         radius=radius,
-#         sagitta_constraint=LengthConstraint.SHORT,
-#     )
+def test_tan2_center_on_1():
+    """2 tangents & center on"""
+    c1 = PolarLine((0, 0), 4, -20, length_mode=LengthMode.HORIZONTAL)
+    c2 = Line((4, -2), (4, 2))
+    c3_center_on = Line((3, -2), (3, 2))
+    tan2_on_edge = Edge.make_constrained_arcs(
+        (c1, Tangency.UNQUALIFIED),
+        (c2, Tangency.UNQUALIFIED),
+        center_on=c3_center_on,
+    )
+    assert len(tan2_on_edge) == 1
 
 
-# # 2 lines & radius
-
-# # 2 points & radius
-# p1 = Vector(0, 0, 0)
-# p2 = Vector(3, 0, 0)
-# tan2_rad_pnts = Edge().make_constrained_arcs(p1, p2, radius=3)
-
-# #
-# # 2 tangents & center on
-# c1 = PolarLine((0, 0), 4, -20, length_mode=LengthMode.HORIZONTAL)
-# c2 = Line((4, -2), (4, 2))
-# c3_center_on_this_line = Line((3, -2), (3, 2))
-# c4 = Line((0, 0), (0, 10))
-# for c in (c1, c2, c3_center_on_this_line, c4):
-#     c.color = "LightGrey"
-# tan2_on_edge = Edge.make_constrained_arcs(
-#     (c1, PositionConstraint.UNQUALIFIED),
-#     (c2, PositionConstraint.UNQUALIFIED),
-#     center_on=c3_center_on_this_line,
-# )[0]
-# l1 = Line(tan2_on_edge @ 0, (0, 0))
-# l2 = JernArc(tan2_on_edge @ 1, tan2_on_edge % 1, tan2_on_edge.radius, 45)
-# l3 = IntersectingLine(l2 @ 1, l2 % 1, c4)
-
-# #
-# # tangent & center
-# c5 = PolarLine((0, 0), 4, 60)
-# center1 = Vector(2, 1)
-# tan_center = Edge.make_constrained_arcs(
-#     (c5, PositionConstraint.UNQUALIFIED), center=center1
-# )
-# #
-# # point & center
-# p3 = Vector(-2.5, 1.5)
-# center2 = Vector(-2, 1)
-# pnt_center = Edge.make_constrained_arcs(p3, center=center2)
-
-# #
-# # tangent, radius, center on
-# # tan_rad_on = Edge.make_constrained_arcs(
-# #     (c1, PositionConstraint.UNQUALIFIED), radius=1, center_on=c3_center_on_this_line
-# # )
-# tan_rad_on = Edge.make_constrained_arcs(c1, radius=1, center_on=c3_center_on_this_line)
-
-# print(f"{len(tan_rad_on)=}")
-
-# objects = [
-#     (c1, PositionConstraint.ENCLOSED),
-#     (Vector(1, 2, 3), None),
-#     (Edge.make_line((0, 0), (1, 0)), PositionConstraint.UNQUALIFIED),
-# ]
-# s = sorted(objects, key=lambda t: not issubclass(type(t[0]), Edge))
-# print(f"{objects=},{s=}")
-# #
-# # 3 tangents
-# c6 = PolarLine((0, 0), 4, 40)
-# c7 = CenterArc((0, 0), 4, 0, 90)
-# tan3 = Edge.make_constrained_arcs(
-#     (c5, PositionConstraint.UNQUALIFIED),
-#     (c6, PositionConstraint.UNQUALIFIED),
-#     (c7, PositionConstraint.UNQUALIFIED),
-# )
-# tan3 = Edge.make_constrained_arcs(c5, c6, c7)
-
-# # v = Vertex(1, 2, 0)
-# # v.color = "Teal"
-# # show(e1, e2, tan2_rad, v)
-
-# r_left, r_right = 0.75, 1.0
-# r_bottom, r_top = 6, 8
-# con_circle_left = CenterArc((-2, 0), r_left, 0, 360)
-# con_circle_right = CenterArc((2, 0), r_right, 0, 360)
-# for c in [con_circle_left, con_circle_right]:
-#     c.color = "LightGrey"
-# # for con1, con2 in itertools.product(PositionConstraint, PositionConstraint):
-# #     try:
-# #         egg1 = Edge.make_constrained_arcs(
-# #             (c8, con1),
-# #             (c9, con2),
-# #             radius=10,
-# #         )
-# #     except:
-# #         print(f"{con1},{con2} failed")
-# #     else:
-# #         print(f"{con1},{con2} {len(egg1)=}")
-# egg_bottom = Edge.make_constrained_arcs(
-#     (con_circle_right, PositionConstraint.OUTSIDE),
-#     (con_circle_left, PositionConstraint.OUTSIDE),
-#     radius=r_bottom,
-# ).sort_by(Axis.Y)[0]
-# egg_top = Edge.make_constrained_arcs(
-#     (con_circle_right, PositionConstraint.ENCLOSING),
-#     (con_circle_left, PositionConstraint.ENCLOSING),
-#     radius=r_top,
-# ).sort_by(Axis.Y)[-1]
-# egg_right = ThreePointArc(
-#     egg_bottom.vertices().sort_by(Axis.X)[-1],
-#     con_circle_right @ 0,
-#     egg_top.vertices().sort_by(Axis.X)[-1],
-# )
-# egg_left = ThreePointArc(
-#     egg_bottom.vertices().sort_by(Axis.X)[0],
-#     con_circle_left @ 0.5,
-#     egg_top.vertices().sort_by(Axis.X)[0],
-# )
-
-# egg_plant = Wire([egg_left, egg_top, egg_right, egg_bottom])
+def test_tan_center_on_1():
+    """1 tangent & center on"""
+    c5 = PolarLine((0, 0), 4, 60)
+    tan_center = Edge.make_constrained_arcs((c5, Tangency.UNQUALIFIED), center=(2, 1))
+    assert len(tan_center) == 1
+    assert tan_center[0].is_closed
 
 
-# make_constrained_arcs
+def test_pnt_center_1():
+    """pnt & center"""
+    pnt_center = Edge.make_constrained_arcs((-2.5, 1.5), center=(-2, 1))
+    assert len(pnt_center) == 1
+    assert pnt_center[0].is_closed
 
 
-# class TestConstrainedArcs(unittest.TestCase):
-#     def test_close(self):
-#         self.assertAlmostEqual(
-#             Edge.make_circle(1, end_angle=180).close().length, math.pi + 2, 5
-#         )
-#         self.assertAlmostEqual(Edge.make_circle(1).close().length, 2 * math.pi, 5)
+def test_tan_rad_center_on_1():
+    """tangent, radius, center on"""
+    c1 = PolarLine((0, 0), 4, -20, length_mode=LengthMode.HORIZONTAL)
+    c3_center_on = Line((3, -2), (3, 2))
+    tan_rad_on = Edge.make_constrained_arcs(
+        (c1, Tangency.UNQUALIFIED), radius=1, center_on=c3_center_on
+    )
+    assert len(tan_rad_on) == 1
+    assert tan_rad_on[0].is_closed
+
+
+def test_tan3_1():
+    """3 tangents"""
+    c5 = PolarLine((0, 0), 4, 60)
+    c6 = PolarLine((0, 0), 4, 40)
+    c7 = CenterArc((0, 0), 4, 0, 90)
+    tan3 = Edge.make_constrained_arcs(
+        (c5, Tangency.UNQUALIFIED),
+        (c6, Tangency.UNQUALIFIED),
+        (c7, Tangency.UNQUALIFIED),
+    )
+    assert len(tan3) == 1
+    assert not tan3[0].is_closed
+
+
+def test_eggplant():
+    """complex set of 4 arcs"""
+    r_left, r_right = 0.75, 1.0
+    r_bottom, r_top = 6, 8
+    con_circle_left = CenterArc((-2, 0), r_left, 0, 360)
+    con_circle_right = CenterArc((2, 0), r_right, 0, 360)
+    egg_bottom = Edge.make_constrained_arcs(
+        (con_circle_right, Tangency.OUTSIDE),
+        (con_circle_left, Tangency.OUTSIDE),
+        radius=r_bottom,
+    ).sort_by(Axis.Y)[0]
+    egg_top = Edge.make_constrained_arcs(
+        (con_circle_right, Tangency.ENCLOSING),
+        (con_circle_left, Tangency.ENCLOSING),
+        radius=r_top,
+    ).sort_by(Axis.Y)[-1]
+    egg_right = ThreePointArc(
+        egg_bottom.vertices().sort_by(Axis.X)[-1],
+        con_circle_right @ 0,
+        egg_top.vertices().sort_by(Axis.X)[-1],
+    )
+    egg_left = ThreePointArc(
+        egg_bottom.vertices().sort_by(Axis.X)[0],
+        con_circle_left @ 0.5,
+        egg_top.vertices().sort_by(Axis.X)[0],
+    )
+
+    egg_plant = Wire([egg_left, egg_top, egg_right, egg_bottom])
+    assert egg_plant.is_closed
+    egg_plant_edges = egg_plant.edges().sort_by(egg_plant)
+    common_vertex_cnt = sum(
+        topo_explore_common_vertex(egg_plant_edges[i], egg_plant_edges[(i + 1) % 4])
+        is not None
+        for i in range(4)
+    )
+    assert common_vertex_cnt == 4
+
+    # C1 continuity
+    assert all(
+        (egg_plant_edges[i] % 1 - egg_plant_edges[(i + 1) % 4] % 0).length < TOLERANCE
+        for i in range(4)
+    )