791: fix support for a source referencing an ancestor repeat target

pyxform/survey.py

@@ -113,8 +113,8 @@ def is_repeat(e: SurveyElement) -> bool:
     if reference_parent:
         # The LCAR may or may not be the closest ancestor repeat for source or target,
         # but there's always at least the LCAR, so a check for None isn't needed.
-        source_car, _ = next(source.iter_ancestors(condition=is_repeat), None)
-        target_car, _ = next(target.iter_ancestors(condition=is_repeat), None)
+        source_car, _ = next(source.iter_ancestors(condition=is_repeat), (None, None))
+        target_car, _ = next(target.iter_ancestors(condition=is_repeat), (None, None))
         # May return None if LCAR is a child of the Survey, or only non-repeating group(s).
         lcar_not_in_repeat = next(lcar.iter_ancestors(condition=is_repeat), None) is None
 

pyxform/survey_element.py

@@ -94,6 +94,9 @@ def __setattr__(self, key, value):
             self._survey_element_xpath = None
         super().__setattr__(key, value)
 
+    def __repr__(self):
+        return f"""{super().__repr__()}(name="{self.name}")"""
+
     def __init__(
         self,
         name: str,
@@ -195,13 +198,6 @@ def lowest_common_ancestor(
         """
         Get the relation type, steps from self, steps from other, and the common ancestor.
         """
-
-        # Quick check for immediate relation.
-        if self.parent is other:
-            return "Parent (other)", 1, 0, other
-        elif other.parent is self:
-            return "Parent (self)", 0, 1, self
-
         # Filtering
         if group_type:
             type_filter = {group_type}
@@ -211,10 +207,10 @@ def lowest_common_ancestor(
         # Traversal tracking
         self_ancestors = {}
         other_ancestors = {}
-        self_current = self
-        other_current = other
-        self_distance = 0
-        other_distance = 0
+        self_current = self.parent
+        other_current = other.parent
+        self_distance = 1
+        other_distance = 1
         lca = None
 
         # Traverse up both ancestor chains as far as necessary.