Add import report service

app/services/imports/import_report_service.rb

@@ -0,0 +1,27 @@
+module Imports
+  class ImportReportService
+    def initialize(storage_service, old_organisation_ids, logger = Rails.logger)
+      @storage_service = storage_service
+      @logger = logger
+      @old_organisation_ids = old_organisation_ids
+    end
+
+    BYTE_ORDER_MARK = "\uFEFF".freeze # Required to ensure Excel always reads CSV as UTF-8
+
+    def create_report(report_directory)
+      write_missing_data_coordinators_report(report_directory)
+    end
+
+    def write_missing_data_coordinators_report(report_directory)
+      csv_string = "Organisation ID,Old Organisation ID,Organisation Name\n"
+      @old_organisation_ids.each do |old_organisation_id|
+        organisation = Organisation.find_by(old_visible_id: old_organisation_id)
+        if organisation.users.none?(&:data_coordinator?)
+          csv_string += "#{organisation.id},#{old_organisation_id},#{organisation.name}\n"
+        end
+      end
+
+      @storage_service.write_file("#{report_directory}/organisations_without_data_coordinators.csv", BYTE_ORDER_MARK + csv_string)
+    end
+  end
+end

spec/services/imports/import_report_service_spec.rb

@@ -0,0 +1,39 @@
+require "rails_helper"
+
+RSpec.describe Imports::ImportReportService do
+  subject(:report_service) { described_class.new(storage_service, old_organisation_ids) }
+
+  let(:storage_service) { instance_double(Storage::S3Service) }
+
+  context "when all organisations have data coordinators" do
+    let(:organisation) { create(:organisation, old_visible_id: "1") }
+    let(:old_organisation_ids) { [organisation.old_visible_id] }
+
+    before do
+      create(:user, :data_coordinator, organisation:)
+    end
+
+    it "writes an empty organisations without a data coordinators report" do
+      expect(storage_service).to receive(:write_file).with("report_directory/organisations_without_data_coordinators.csv", "\uFEFFOrganisation ID,Old Organisation ID,Organisation Name\n")
+
+      report_service.create_report("report_directory")
+    end
+  end
+
+  context "when some organisations have no data coordinators" do
+    let(:organisation) { create(:organisation, old_visible_id: "") }
+    let(:organisation2) { create(:organisation, old_visible_id: "2") }
+    let(:organisation3) { create(:organisation, old_visible_id: "3") }
+    let(:old_organisation_ids) { [organisation.old_visible_id, organisation2.old_visible_id, organisation3.old_visible_id] }
+
+    before do
+      create(:user, :data_coordinator, organisation:)
+    end
+
+    it "writes an empty organisations without a data coordinators report" do
+      expect(storage_service).to receive(:write_file).with("report_directory/organisations_without_data_coordinators.csv", "\uFEFFOrganisation ID,Old Organisation ID,Organisation Name\n#{organisation2.id},2,#{organisation2.name}\n#{organisation3.id},3,#{organisation3.name}\n")
+
+      report_service.create_report("report_directory")
+    end
+  end
+end