Merge branch 'georgekoltsov/64377-add-better-log-msg-to-members-mapper' into 'master'

Add better error message to MembersMapper#ensure_default_member!

See merge request gitlab-org/gitlab-ce!30838

changelogs/unreleased/georgekoltsov-64377-add-better-log-msg-to-members-mapper.yml

+---
+title: When GitLab import fails during importer user mapping step, add an explicit
+  error message mentioning importer
+merge_request: 30838
+author:
+type: other

lib/gitlab/import_export/members_mapper.rb

@@ -50,6 +50,8 @@ module Gitlab
         @project.project_members.destroy_all # rubocop: disable DestroyAll
 
         ProjectMember.create!(user: @user, access_level: ProjectMember::MAINTAINER, source_id: @project.id, importing: true)
+      rescue => e
+        raise e, "Error adding importer user to project members. #{e.message}"
       end
 
       def add_team_member(member, existing_user = nil)

spec/lib/gitlab/import_export/members_mapper_spec.rb

@@ -154,5 +154,15 @@ describe Gitlab::ImportExport::MembersMapper do
         expect(members_mapper.map[exported_user_id]).to eq(user2.id)
       end
     end
+
+    context 'when importer mapping fails' do
+      let(:exception_message) { 'Something went wrong' }
+
+      it 'includes importer specific error message' do
+        expect(ProjectMember).to receive(:create!).and_raise(StandardError.new(exception_message))
+
+        expect { members_mapper.map }.to raise_error(StandardError, "Error adding importer user to project members. #{exception_message}")
+      end
+    end
   end
 end