Add generate_missing_answers_report task and method

app/services/imports/import_report_service.rb

@@ -84,5 +84,36 @@ module Imports
 
       @logger.info("Unassigned logs report available in s3 import bucket at #{report_name}")
     end
+
+    def generate_missing_answers_report(report_suffix)
+      Rails.logger.info("Generating missing imported lettings logs answers report")
+
+      rep = CSV.generate do |report|
+        headers = ["Missing answers", "Total number of affected logs"]
+        report << headers
+
+        unanswered_question_counts = {}
+
+        LettingsLog.where.not(old_id: nil).where(status: "in_progress").each do |lettings_log|
+          applicable_questions = lettings_log.form.subsections.map { |s| s.applicable_questions(lettings_log).select { |q| q.enabled?(lettings_log) } }.flatten
+          unanswered_questions = applicable_questions.filter { |q| q.unanswered?(lettings_log) }.map(&:id) - lettings_log.optional_fields
+
+          if unanswered_question_counts[unanswered_questions.join(", ")].present?
+            unanswered_question_counts[unanswered_questions.join(", ")] += 1
+          else
+            unanswered_question_counts[unanswered_questions.join(", ")] = 1
+          end
+        end
+
+        unanswered_question_counts.each do |missing_answers, count|
+          report << [missing_answers, count]
+        end
+      end
+
+      report_name = "MissingAnswersReport_#{report_suffix}.csv"
+      @storage_service.write_file(report_name, BYTE_ORDER_MARK + rep)
+
+      @logger.info("Missing answers report available in s3 import bucket at #{report_name}")
+    end
   end
 end

lib/tasks/full_import.rake

@@ -117,6 +117,15 @@ namespace :import do
     Imports::ImportReportService.new(s3_service, institutions_csv).create_reports(institutions_csv_name)
   end
 
+  desc "Generate migrated logs report"
+  task :generate_missing_answers_report, %i[file_suffix] => :environment do |_task, args|
+    file_suffix = args[:file_suffix]
+    raise "Usage: rake import:generate_reports['file_suffix']" if file_suffix.blank?
+
+    s3_service = Storage::S3Service.new(PlatformHelper.is_paas? ? Configuration::PaasConfigurationService.new : Configuration::EnvConfigurationService.new, ENV["IMPORT_PAAS_INSTANCE"])
+    Imports::ImportReportService.new(s3_service, nil).generate_missing_answers_report(file_suffix)
+  end
+
   desc "Run import from logs step to end"
   task :logs_onwards, %i[institutions_csv_name] => %i[environment logs trigger_invites generate_reports]
 

spec/fixtures/files/imported_lettings_logs_missing_answers_report.csv

@@ -0,0 +1,2 @@
+Missing answers,Total number of affected logs
+age1_known,11

spec/lib/tasks/full_import_spec.rb

@@ -54,6 +54,32 @@ describe "full import", type: :task do
     end
   end
 
+  describe "import:generate_missing_answers_report" do
+    subject(:task) { Rake::Task["import:generate_missing_answers_report"] }
+
+    before do
+      Rake.application.rake_require("tasks/full_import")
+      Rake::Task.define_task(:environment)
+      task.reenable
+    end
+
+    context "when generating a missing answers report" do
+      let(:import_report_service) { instance_double(Imports::ImportReportService) }
+
+      before do
+        allow(Imports::ImportReportService).to receive(:new).and_return(import_report_service)
+        allow(ENV).to receive(:[]).with("VCAP_SERVICES").and_return("dummy")
+      end
+
+      it "creates a missing answers report" do
+        expect(Storage::S3Service).to receive(:new).with(paas_config_service, instance_name)
+        expect(Imports::ImportReportService).to receive(:new).with(storage_service, nil)
+        expect(import_report_service).to receive(:generate_missing_answers_report).with("some_name")
+        task.invoke("some_name")
+      end
+    end
+  end
+
   describe "import:initial" do
     subject(:task) { Rake::Task["import:initial"] }
 

spec/services/imports/import_report_service_spec.rb

@@ -98,4 +98,25 @@ RSpec.describe Imports::ImportReportService do
       end
     end
   end
+
+  describe "#generate_missing_answers_report" do
+    context "when there are in progress imported logs" do
+      let(:institutions_csv) { nil }
+      let(:expected_content) { File.read("spec/fixtures/files/imported_lettings_logs_missing_answers_report.csv") }
+
+      before do
+        create_list(:lettings_log, 11, :completed, age1_known: nil) do |log, _i|
+          log.old_id = Faker::Name.initials(number: 10)
+          log.save!
+        end
+        create_list(:lettings_log, 2, :completed, age1_known: nil)
+      end
+
+      it "generates a csv with expected missing fields" do
+        expect(storage_service).to receive(:write_file).with("MissingAnswersReport_report_suffix.csv", "#{expected_content}")
+
+        report_service.generate_missing_answers_report("report_suffix")
+      end
+    end
+  end
 end