diff --git a/test/services/unit/assignment_service_test.rb b/test/services/unit/assignment_service_test.rb
index dd88d681..f7599d74 100644
--- a/test/services/unit/assignment_service_test.rb
+++ b/test/services/unit/assignment_service_test.rb
@@ -114,6 +114,86 @@ class AssignmentServiceTest < ForemanAnsibleDirectorTestCase
             )
             assert_equal 2, target_assignments.count
           end
+
+          test 'does nothing for empty assignments' do
+            FactoryBot.create(
+              :ansible_content_assignment,
+              consumable: @collection_role,
+              assignable: @host
+            )
+
+            ::ForemanAnsibleDirector::AssignmentService.create_bulk_assignments(assignments: [])
+
+            assert_equal 1, ::ForemanAnsibleDirector::AnsibleContentAssignment.where(assignable: @host).count
+          end
+
+          test 'raises and keeps existing assignments when source is missing' do
+            existing_assignment = FactoryBot.create(
+              :ansible_content_assignment,
+              consumable: @collection_role,
+              assignable: @host
+            )
+
+            assert_raises(ActiveRecord::StatementInvalid) do
+              ::ForemanAnsibleDirector::AssignmentService.create_bulk_assignments(
+                assignments: [
+                  { source: { type: 'ACR', id: -1 }, target: { type: 'HOST', id: @host.id } }
+                ]
+              )
+            end
+
+            assert_equal [existing_assignment], ::ForemanAnsibleDirector::AnsibleContentAssignment.where(
+              assignable: @host
+            ).to_a
+          end
+
+          test 'raises and keeps existing assignments when target is missing' do
+            existing_assignment = FactoryBot.create(
+              :ansible_content_assignment,
+              consumable: @collection_role,
+              assignable: @host
+            )
+
+            assert_raises(NoMethodError) do
+              ::ForemanAnsibleDirector::AssignmentService.create_bulk_assignments(
+                assignments: [
+                  { source: { type: 'ACR', id: @collection_role.id }, target: { type: 'HOST', id: -1 } }
+                ]
+              )
+            end
+
+            assert_equal [existing_assignment], ::ForemanAnsibleDirector::AnsibleContentAssignment.where(
+              assignable: @host
+            ).to_a
+          end
+
+          test 'rolls back all target changes when a later assignment fails' do
+            existing_assignment = FactoryBot.create(
+              :ansible_content_assignment,
+              consumable: @collection_role,
+              assignable: @host
+            )
+
+            collection2 = FactoryBot.create(:ansible_collection, organization: @organization)
+            collection_version2 = FactoryBot.create(:content_unit_version, :for_collection, versionable: collection2)
+            collection_role2 = FactoryBot.create(
+              :ansible_collection_role,
+              ansible_collection_version: collection_version2
+            )
+
+            assert_raises(ActiveRecord::StatementInvalid) do
+              ::ForemanAnsibleDirector::AssignmentService.create_bulk_assignments(
+                assignments: [
+                  { source: { type: 'ACR', id: collection_role2.id }, target: { type: 'HOST', id: @host.id } },
+                  { source: { type: 'ACR', id: -1 }, target: { type: 'HOST', id: @host.id } }
+                ]
+              )
+            end
+
+            assert_equal [existing_assignment], ::ForemanAnsibleDirector::AnsibleContentAssignment.where(
+              assignable: @host
+            ).to_a
+          end
         end
 
         describe '#finder' do