Add unique index and rake task

app/services/imports/local_authorities_service.rb

@@ -17,6 +17,7 @@ module Imports
             start_date: Time.zone.local(row["start_year"], 4, 1),
             end_date: (Time.zone.local(row["end_year"], 3, 31) if row["end_year"]),
             previous_location_only: row["previous_location_only"] || false },
+          unique_by: %i[code],
         )
         @count += 1
       end

db/migrate/20230308101826_create_local_authorities.rb

@@ -6,6 +6,7 @@ class CreateLocalAuthorities < ActiveRecord::Migration[7.0]
       t.datetime :start_date
       t.datetime :end_date
       t.boolean :previous_location_only, default: false
+      t.index %w[code], name: "index_local_authority_code", unique: true
 
       t.timestamps
     end

db/schema.rb

@@ -297,6 +297,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_03_08_101826) do
     t.boolean "previous_location_only", default: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["code"], name: "index_local_authority_code", unique: true
   end
 
   create_table "location_deactivation_periods", force: :cascade do |t|

lib/tasks/local_authorities.rake

@@ -0,0 +1,13 @@
+namespace :data_import do
+  desc "Import local authorities data"
+  task :local_authorities, %i[path] => :environment do |_task, args|
+    path = args[:path]
+
+    raise "Usage: rake data_import:local_authorities['path/to/csv_file']" if path.blank?
+
+    service = Imports::LocalAuthoritiesService.new(path:)
+    service.call
+
+    pp "Created/updated #{service.count} local authority records" unless Rails.env.test?
+  end
+end

spec/fixtures/files/local_authorities.csv

@@ -0,0 +1,6 @@
+code,la_name,start_year,end_year,previous_location_only
+S12000033,Aberdeen City,2021,,true
+S12000034,Aberdeenshire,2021,,true
+E07000223,Adur,2021,,
+E07000032,Amber Valley,2021,,
+S12000041,Angus,2021,,true

spec/lib/tasks/local_authorities_import_spec.rb

@@ -0,0 +1,42 @@
+require "rails_helper"
+require "rake"
+
+RSpec.describe "data_import" do
+  describe ":local_authorities", type: :task do
+    subject(:task) { Rake::Task["data_import:local_authorities"] }
+
+    before do
+      Rake.application.rake_require("tasks/local_authorities")
+      Rake::Task.define_task(:environment)
+      task.reenable
+    end
+
+    context "when the rake task is run" do
+      let(:local_authorities_file_path) { "./spec/fixtures/files/local_authorities.csv" }
+      let(:wrong_file_path) { "/test/no_csv_here.csv" }
+
+      it "creates new local authorities records" do
+        expect { task.invoke(local_authorities_file_path) }.to change(LocalAuthority, :count).by(5)
+        expect(LocalAuthority.where(code: "S12000041").exists?).to be true
+      end
+
+      it "raises an error when no path is given" do
+        expect { task.invoke(nil) }.to raise_error(RuntimeError, "Usage: rake data_import:local_authorities['path/to/csv_file']")
+      end
+
+      it "raises an error when no file exists at the given path" do
+        expect { task.invoke(wrong_file_path) }.to raise_error(Errno::ENOENT)
+      end
+
+      context "when a record already exists with a matching code index" do
+        let!(:local_authority) { LocalAuthority.create(code: "S12000041", la_name: "Angus", start_date: Time.zone.local(2021, 4, 1), previous_location_only: false) }
+
+        it "updates local authority if the record is matched on code" do
+          task.invoke(local_authorities_file_path)
+          local_authority.reload
+          expect(local_authority.previous_location_only).to eq(true)
+        end
+      end
+    end
+  end
+end