diff --git a/openedx/core/djangoapps/content/block_structure/tests/helpers.py b/openedx/core/djangoapps/content/block_structure/tests/helpers.py
index 93655c79e16e..406fde512671 100644
--- a/openedx/core/djangoapps/content/block_structure/tests/helpers.py
+++ b/openedx/core/djangoapps/content/block_structure/tests/helpers.py
@@ -7,6 +7,7 @@
 from uuid import uuid4
 from unittest.mock import patch
 
+from opaque_keys.edx.keys import CourseKey
 from opaque_keys.edx.locator import BlockUsageLocator, CourseLocator
 
 from xmodule.modulestore.exceptions import ItemNotFoundError
@@ -274,10 +275,14 @@ def create_block_structure(self, children_map, block_structure_cls=BlockStructur
         # create empty block structure
         block_structure = block_structure_cls(root_block_usage_key=self.block_key_factory(0))
 
-        # _add_relation
+        # _add_relation and blocks
         for parent, children in enumerate(children_map):
+            if isinstance(block_structure, BlockStructureBlockData):
+                block_structure._get_or_create_block(self.block_key_factory(parent))  # pylint: disable=protected-access
             for child in children:
                 block_structure._add_relation(self.block_key_factory(parent), self.block_key_factory(child))  # pylint: disable=protected-access
+                if isinstance(block_structure, BlockStructureBlockData):
+                    block_structure._get_or_create_block(self.block_key_factory(child))  # pylint: disable=protected-access
         return block_structure
 
     def get_parents_map(self, children_map):
diff --git a/openedx/core/djangoapps/content/block_structure/tests/test_factory.py b/openedx/core/djangoapps/content/block_structure/tests/test_factory.py
index b9fb8c5e1077..00efa393d8fa 100644
--- a/openedx/core/djangoapps/content/block_structure/tests/test_factory.py
+++ b/openedx/core/djangoapps/content/block_structure/tests/test_factory.py
@@ -5,6 +5,7 @@
 import pytest
 from django.test import TestCase
 
+from opaque_keys.edx.keys import CourseKey
 from xmodule.modulestore.exceptions import ItemNotFoundError
 
 from ..exceptions import BlockStructureNotFound
@@ -18,14 +19,22 @@ class TestBlockStructureFactory(TestCase, ChildrenMapTestMixin):
     Tests for BlockStructureFactory
     """
 
+    def block_key_factory(self, block_id):
+        """
+        Returns a usage_key object for the given block_id.
+        This overrides the method in the ChildrenMapTestMixin.
+        """
+        return CourseKey.from_string("course-v1:org+course+run").make_usage_key("html", str(block_id))
+
     def setUp(self):
         super().setUp()
         self.children_map = self.SIMPLE_CHILDREN_MAP
         self.modulestore = MockModulestoreFactory.create(self.children_map, self.block_key_factory)
 
     def test_from_modulestore(self):
+        usage_key = CourseKey.from_string("course-v1:org+course+run").make_usage_key("html", "0")
         block_structure = BlockStructureFactory.create_from_modulestore(
-            root_block_usage_key=0, modulestore=self.modulestore
+            root_block_usage_key=usage_key, modulestore=self.modulestore
         )
         self.assert_block_structure(block_structure, self.children_map)
 
@@ -48,15 +57,18 @@ def test_from_cache(self):
 
     def test_from_cache_none(self):
         store = BlockStructureStore(MockCache())
+        # Non-existent usage key
+        usage_key = CourseKey.from_string("course-v1:org+course+run").make_usage_key("html", "0")
         with pytest.raises(BlockStructureNotFound):
             BlockStructureFactory.create_from_store(
-                root_block_usage_key=0,
+                root_block_usage_key=usage_key,
                 block_structure_store=store,
             )
 
     def test_new(self):
+        usage_key = CourseKey.from_string("course-v1:org+course+run").make_usage_key("html", "0")
         block_structure = BlockStructureFactory.create_from_modulestore(
-            root_block_usage_key=0, modulestore=self.modulestore
+            root_block_usage_key=usage_key, modulestore=self.modulestore
         )
         new_structure = BlockStructureFactory.create_new(
             block_structure.root_block_usage_key,