Preserve epic child-parent association when using Bulk Import

  - This change updated Bulk Import epics import to preserve
  child-parent association in order to more accurately migrate
  group epics from source GitLab to destination

ee/changelogs/unreleased/georgekoltsov-bulk-import-epic-parent-child-association.yml

+---
+title: Preserve Epic parent-child association when importing using Bulk Import
+merge_request: 52662
+author:
+type: changed

ee/lib/ee/bulk_imports/groups/graphql/get_epics_query.rb

@@ -21,6 +21,7 @@ module EE
                     has_next_page: hasNextPage
                   }
                   nodes {
+                    iid
                     title
                     description
                     state
@@ -33,6 +34,14 @@ module EE
                     due_date_is_fixed: dueDateIsFixed
                     relative_position: relativePosition
                     confidential
+                    parent {
+                      iid
+                    }
+                    children {
+                      nodes {
+                        iid
+                      }
+                    }
                   }
                 }
               }

ee/lib/ee/bulk_imports/groups/loaders/epics_loader.rb

@@ -5,16 +5,20 @@ module EE
     module Groups
       module Loaders
         class EpicsLoader
+          NotAllowedError = Class.new(StandardError)
+
           def initialize(options = {})
             @options = options
           end
 
           def load(context, data)
-            ::Epics::CreateService.new(
-              context.entity.group,
-              context.current_user,
-              data
-            ).execute
+            raise NotAllowedError unless context.current_user.can?(:create_epic, context.group)
+
+            # Use `Epic` directly when creating new epics
+            # instead of `Epics::CreateService` since several
+            # attributes like author_id (which might not be current_user),
+            # group_id, parent, children need to be custom set
+            ::Epic.create!(data)
           end
         end
       end

ee/lib/ee/bulk_imports/groups/pipelines/epics_pipeline.rb

@@ -11,6 +11,7 @@ module EE
             query: EE::BulkImports::Groups::Graphql::GetEpicsQuery
 
           transformer ::BulkImports::Common::Transformers::ProhibitedAttributesTransformer
+          transformer EE::BulkImports::Groups::Transformers::EpicAttributesTransformer
 
           loader EE::BulkImports::Groups::Loaders::EpicsLoader
 

ee/lib/ee/bulk_imports/groups/transformers/epic_attributes_transformer.rb

+# frozen_string_literal: true
+
+module EE
+  module BulkImports
+    module Groups
+      module Transformers
+        class EpicAttributesTransformer
+          def initialize(*args); end
+
+          def transform(context, data)
+            data
+              .then { |data| add_group_id(context, data) }
+              .then { |data| add_author_id(context, data) }
+              .then { |data| add_parent(context, data) }
+              .then { |data| add_children(context, data) }
+          end
+
+          private
+
+          def add_group_id(context, data)
+            data.merge('group_id' => context.entity.namespace_id)
+          end
+
+          def add_author_id(context, data)
+            data.merge('author_id' => context.current_user.id)
+          end
+
+          def add_parent(context, data)
+            data.merge(
+              'parent' => context.entity.group.epics.find_by_iid(data.dig('parent', 'iid'))
+            )
+          end
+
+          def add_children(context, data)
+            nodes = Array.wrap(data.dig('children', 'nodes'))
+            children_iids = nodes.filter_map { |child| child['iid'] }
+
+            data.merge('children' => context.entity.group.epics.where(iid: children_iids)) # rubocop: disable CodeReuse/ActiveRecord
+          end
+        end
+      end
+    end
+  end
+end

ee/spec/lib/ee/bulk_imports/groups/loaders/epics_loader_spec.rb

@@ -6,18 +6,25 @@ RSpec.describe EE::BulkImports::Groups::Loaders::EpicsLoader do
   describe '#load' do
     let(:user) { create(:user) }
     let(:group) { create(:group) }
-    let(:entity) { create(:bulk_import_entity, group: group) }
+    let(:bulk_import) { create(:bulk_import, user: user) }
+    let(:entity) { create(:bulk_import_entity, bulk_import: bulk_import, group: group) }
     let(:context) { BulkImports::Pipeline::Context.new(entity) }
 
     let(:data) do
       {
         'title' => 'epic1',
         'state' => 'opened',
-        'confidential' => false
+        'confidential' => false,
+        'iid' => 1,
+        'author_id' => user.id,
+        'group_id' => group.id
       }
     end
 
-    subject { described_class.new }
+    before do
+      stub_licensed_features(epics: true)
+      group.add_owner(user)
+    end
 
     it 'creates the epic' do
       expect { subject.load(context, data) }.to change(::Epic, :count).by(1)

ee/spec/lib/ee/bulk_imports/groups/pipelines/epics_pipeline_spec.rb

@@ -6,18 +6,25 @@ RSpec.describe EE::BulkImports::Groups::Pipelines::EpicsPipeline do
   let(:user) { create(:user) }
   let(:group) { create(:group) }
   let(:cursor) { 'cursor' }
+  let(:bulk_import) { create(:bulk_import, user: user) }
   let(:entity) do
     create(
       :bulk_import_entity,
       source_full_path: 'source/full/path',
       destination_name: 'My Destination Group',
       destination_namespace: group.full_path,
-      group: group
+      group: group,
+      bulk_import: bulk_import
     )
   end
 
   let(:context) { BulkImports::Pipeline::Context.new(entity) }
 
+  before do
+    stub_licensed_features(epics: true)
+    group.add_owner(user)
+  end
+
   describe '#run' do
     it 'imports group epics into destination group' do
       first_page = extractor_data(has_next_page: true, cursor: cursor)
@@ -82,7 +89,8 @@ RSpec.describe EE::BulkImports::Groups::Pipelines::EpicsPipeline do
     it 'has transformers' do
       expect(described_class.transformers)
         .to contain_exactly(
-          { klass: BulkImports::Common::Transformers::ProhibitedAttributesTransformer, options: nil }
+          { klass: BulkImports::Common::Transformers::ProhibitedAttributesTransformer, options: nil },
+          { klass: EE::BulkImports::Groups::Transformers::EpicAttributesTransformer, options: nil }
         )
     end
 

ee/spec/lib/ee/bulk_imports/groups/transformers/epic_attributes_transformer_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe EE::BulkImports::Groups::Transformers::EpicAttributesTransformer do
+  describe '#transform' do
+    let(:user) { create(:user) }
+    let(:group) { create(:group, name: 'My Source Group') }
+    let(:entity) do
+      instance_double(
+        BulkImports::Entity,
+        group: group,
+        namespace_id: group.id
+      )
+    end
+
+    let(:context) do
+      instance_double(
+        BulkImports::Pipeline::Context,
+        current_user: user,
+        entity: entity
+      )
+    end
+
+    let(:data) do
+      {
+        'iid' => '7',
+        'title' => 'Epic Title',
+        'description' => 'Epic Description',
+        'state' => 'opened',
+        'parent' => {
+          'iid' => parent_iid
+        },
+        'children' => {
+          'nodes' => [
+            {
+              'iid' => child_iid
+            }
+          ]
+        }
+      }
+    end
+
+    context 'when parent and child iids are nil' do
+      let(:parent_iid) { nil }
+      let(:child_iid) { nil }
+
+      it 'sets group_id, author_id from context' do
+        transformed_data = subject.transform(context, data)
+
+        expect(transformed_data['group_id']).to eq(group.id)
+        expect(transformed_data['author_id']).to eq(user.id)
+        expect(transformed_data['parent']).to be_nil
+      end
+    end
+
+    context 'when parent and child iids are present' do
+      let(:parent) { create(:epic, group: group) }
+      let(:child) { create(:epic, group: group) }
+      let(:parent_iid) { parent.iid }
+      let(:child_iid) { child.iid }
+
+      it 'sets parent and child epics' do
+        transformed_data = subject.transform(context, data)
+
+        expect(transformed_data['parent']).to eq(parent)
+        expect(transformed_data['children']).to contain_exactly(child)
+      end
+    end
+  end
+end