Remap Unit extra_fields.options node IDs when copying via copy_node (#5860)

* Remap Unit extra_fields.options node IDs when copying via copy_node

When a Unit topic (UNIT modality) is cloned, lesson node IDs and
pre/post test node IDs in extra_fields.options are rewritten to the
IDs of their copies. Entries whose source nodes were not part of the
copy operation (e.g. excluded via excluded_descendants) are dropped.

Adds _remap_unit_options() static helper on CustomContentNodeTreeManager,
calls it in _recurse_to_create_tree() for the deep-copy path and in
_copy() for the shallow-copy path. _deep_copy() and _copy() now return
(nodes, source_copy_id_map) so the map is available to callers;
copy_node() unwraps the tuple and returns only the node list.

* Test Unit extra_fields.options remapping across copy paths

Adds UnitCopyExtraFieldsTestCase covering:
- lesson_objectives keys remapped to cloned lesson PKs (deep and shallow)
- pre_test/post_test values remapped to cloned node PKs (deep and shallow)
- excluded lesson entry dropped from cloned Unit's lesson_objectives
- excluded Unit: copy succeeds with no remap error (deep and shallow)
- resource excluded inside lesson: lesson entry preserved (deep and shallow)
- assessment_objectives, learning_objectives, completion_criteria unchanged
- standalone Unit copy remaps its lesson children correctly
- extra_fields on Course and Lesson topics is copied verbatim

* Remove pre/post test remapping — Unit options contain no such node-ID keys

The pre_test/post_test entries in a Unit's options are assessment items
on the Unit node itself, not separate ContentNode IDs.  Remove the
dead code in _remap_unit_options() and the fantasy test coverage that
accompanied it.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

* test: drop test_standalone_unit_copy_remaps_lesson_children

Reviewer noted this test is redundant — the same behaviour is already
exercised by the deep/shallow copy integration tests for Unit nodes.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

---------

Co-authored-by: Claude Sonnet 4.6 <[email protected]>

Author: rtibblesbot

contentcuration/contentcuration/db/models/manager.py

@@ -9,6 +9,7 @@
 from django.db.utils import OperationalError
 from django_cte import CTEQuerySet
 from le_utils.constants import content_kinds
+from le_utils.constants import modalities
 from mptt.managers import TreeManager
 from mptt.signals import node_moved
 
@@ -359,6 +360,15 @@ def _recurse_to_create_tree(
                 )
             )
         source_copy_id_map[source.id] = copy["id"]
+
+        if self._is_unit_topic(source.kind_id, copy.get("extra_fields")):
+            copy["extra_fields"] = {
+                **copy["extra_fields"],
+                "options": self._remap_unit_options(
+                    copy["extra_fields"]["options"], source_copy_id_map
+                ),
+            }
+
         return copy
 
     def _all_nodes_to_copy(self, node, excluded_descendants):
@@ -394,7 +404,7 @@ def copy_node(
         if progress_tracker:
             progress_tracker.set_total(total_nodes)
 
-        return self._copy(
+        nodes, _ = self._copy(
             node,
             target,
             position,
@@ -406,6 +416,7 @@ def copy_node(
             batch_size,
             progress_tracker=progress_tracker,
         )
+        return nodes
 
     def _copy(
         self,
@@ -424,7 +435,7 @@ def _copy(
         :type progress_tracker: contentcuration.utils.celery.ProgressTracker|None
         """
         if node.rght - node.lft < batch_size:
-            copied_nodes = self._deep_copy(
+            copied_nodes, node_map = self._deep_copy(
                 node,
                 target,
                 position,
@@ -436,7 +447,7 @@ def _copy(
             )
             if progress_tracker:
                 progress_tracker.increment(len(copied_nodes))
-            return copied_nodes
+            return copied_nodes, node_map
         node_copy = self._shallow_copy(
             node,
             target,
@@ -451,8 +462,9 @@ def _copy(
         children = node.get_children().order_by("lft")
         if excluded_descendants:
             children = children.exclude(node_id__in=excluded_descendants.keys())
+        combined_map = {node.id: node_copy.id}
         for child in children:
-            self._copy(
+            _, child_map = self._copy(
                 child,
                 node_copy,
                 "last-child",
@@ -464,7 +476,19 @@ def _copy(
                 batch_size,
                 progress_tracker=progress_tracker,
             )
-        return [node_copy]
+            combined_map.update(child_map)
+
+        if self._is_unit_topic(node.kind_id, node.extra_fields):
+            remapped_extra_fields = {
+                **node_copy.extra_fields,
+                "options": self._remap_unit_options(
+                    node.extra_fields["options"], combined_map
+                ),
+            }
+            self.filter(pk=node_copy.pk).update(extra_fields=remapped_extra_fields)
+            node_copy.extra_fields = remapped_extra_fields
+
+        return [node_copy], combined_map
 
     def _copy_tags(self, source_copy_id_map):
         from contentcuration.models import ContentTag
@@ -582,6 +606,27 @@ def _copy_associated_objects(self, source_copy_id_map):
 
         self._copy_tags(source_copy_id_map)
 
+    @staticmethod
+    def _is_unit_topic(kind_id, extra_fields):
+        return (
+            kind_id == content_kinds.TOPIC
+            and isinstance(extra_fields, dict)
+            and extra_fields.get("options", {}).get("modality") == modalities.UNIT
+        )
+
+    @staticmethod
+    def _remap_unit_options(options, source_copy_id_map):
+        remapped = dict(options)
+
+        if "lesson_objectives" in remapped:
+            remapped["lesson_objectives"] = {
+                source_copy_id_map[old_id]: objectives
+                for old_id, objectives in remapped["lesson_objectives"].items()
+                if old_id in source_copy_id_map
+            }
+
+        return remapped
+
     def _shallow_copy(
         self,
         node,
@@ -665,4 +710,4 @@ def _deep_copy(
 
         self._copy_associated_objects(source_copy_id_map)
 
-        return new_nodes
+        return new_nodes, source_copy_id_map