Fix CleanupGroupImportStatesWithNullUserId post deploy migration

db/post_migrate/20200909161624_cleanup_group_import_states_with_null_user_id.rb

@@ -19,7 +19,6 @@ class CleanupGroupImportStatesWithNullUserId < ActiveRecord::Migration[6.0]
   class Namespace < ActiveRecord::Base
     self.table_name = 'namespaces'
 
-    belongs_to :parent, class_name: 'CleanupGroupImportStatesWithNullUserId::Namespace'
     belongs_to :owner, class_name: 'CleanupGroupImportStatesWithNullUserId::User'
   end
 
@@ -39,6 +38,10 @@ class CleanupGroupImportStatesWithNullUserId < ActiveRecord::Migration[6.0]
       owners.first || parent&.default_owner || owner
     end
 
+    def parent
+      Group.find_by_id(parent_id)
+    end
+
     def owners
       Member.where(type: 'GroupMember', source_type: 'Namespace', source_id: id, requested_at: nil, access_level: OWNER).map(&:user)
     end

spec/migrations/cleanup_group_import_states_with_null_user_id_spec.rb

@@ -61,6 +61,32 @@ RSpec.describe CleanupGroupImportStatesWithNullUserId, :migration,
         expect { group_import_state_3.reload }.to raise_error(ActiveRecord::RecordNotFound)
       end
     end
+
+    context 'when group has parent' do
+      it 'updates user_id with parent group default owner id' do
+        user = users_table.create!(name: 'user4', email: 'user4@example.com', projects_limit: 1)
+        group_1 = namespaces_table.create!(name: 'group_1', path: 'group_1', type: 'Group')
+        create_member(user_id: user.id, type: 'GroupMember', source_type: 'Namespace', source_id: group_1.id, access_level: described_class::Group::OWNER)
+        group_2 = namespaces_table.create!(name: 'group_2', path: 'group_2', type: 'Group', parent_id: group_1.id)
+        group_import_state = group_import_states_table.create!(group_id: group_2.id, user_id: nil, status: 0)
+
+        disable_migrations_output { migrate! }
+
+        expect(group_import_state.reload.user_id).to eq(user.id)
+      end
+    end
+
+    context 'when group has owner_id' do
+      it 'updates user_id with owner_id' do
+        user = users_table.create!(name: 'user', email: 'user@example.com', projects_limit: 1)
+        group = namespaces_table.create!(name: 'group', path: 'group', type: 'Group', owner_id: user.id)
+        group_import_state = group_import_states_table.create!(group_id: group.id, user_id: nil, status: 0)
+
+        disable_migrations_output { migrate! }
+
+        expect(group_import_state.reload.user_id).to eq(user.id)
+      end
+    end
   end
 
   def create_member(options)