extend _findFromPoint to support Vertex (#1853)

* extend _findFromPoint to support Vertex

* Add one test

* Black fix

* Improve coverage

* Switch to ValueError

Author: adam-urbanczyk

cadquery/cq.py

@@ -1413,8 +1413,10 @@ def _findFromPoint(self, useLocalCoords: bool = False) -> Vector:
             p = obj.endPoint()
         elif isinstance(obj, Vector):
             p = obj
+        elif isinstance(obj, Vertex):
+            p = obj.Center()
         else:
-            raise RuntimeError("Cannot convert object type '%s' to vector " % type(obj))
+            raise ValueError(f"Cannot convert object type {type(obj)} to vector.")
 
         if useLocalCoords:
             return self.plane.toLocalCoords(p)

tests/test_cadquery.py

@@ -5917,3 +5917,15 @@ def test_compound_faces_center(self):
         ), "Incorrect center of mass of the compound, expected {}, got {}".format(
             expected_center, compound.Center()
         )
+
+    def test_line_from_vertex(self):
+
+        # select one vertex and create an Edge
+        res = Workplane().rect(1, 1).vertices(">(1,1,0)").line(1, 0)
+
+        # check if an Edge was created
+        assert isinstance(res.val(), Edge)
+
+        # check that errors are handled
+        with raises(ValueError):
+            Workplane().box(1, 1, 1).line(1, 0)