app/mailers/notification_mailer.rb

@@ -17,4 +17,10 @@ class NotificationMailer < ApplicationMailer
     @subject = "New app connected to your storage"
     mail to: @user.email, subject: @subject
   end
+
+  def new_invitations_available
+    @user = params[:user]
+    @subject = "New invitations added to your account"
+    mail to: @user.email, subject: @subject
+  end
 end

app/services/create_invitations.rb

@@ -0,0 +1,17 @@
+class CreateInvitations < ApplicationService
+  def initialize(user:, amount:, notify: true)
+    @user = user
+    @amount = amount
+    @notify = notify
+  end
+
+  def call
+    @amount.times do
+      Invitation.create(user: @user)
+    end
+
+    if @notify
+      NotificationMailer.with(user: @user).new_invitations_available.deliver_later
+    end
+  end
+end

app/views/notification_mailer/new_invitations_available.text.erb

@@ -0,0 +1,11 @@
+Hi <%= @user.display_name.presence || @user.cn %>,
+
+New invitations have just been added to your Kosmos account, so you can invite more people to our cooperative services:
+
+<%= invitations_url %>
+
+Have a nice day!
+
+---
+
+Tip: if you want to invite someone you're meeting in person, log into your account panel on a mobile device and let people scan the invitation QR code from theirs.

spec/services/create_invitations_spec.rb

@@ -0,0 +1,40 @@
+require 'rails_helper'
+
+RSpec.describe CreateInvitations, type: :model do
+  include ActiveJob::TestHelper
+
+  let(:user) { create :user }
+
+  describe "#call" do
+    before do
+      CreateInvitations.call(user: user, amount: 5)
+    end
+
+    after(:each) { clear_enqueued_jobs }
+
+    it "creates the right amount of invitations for the given user" do
+      expect(user.invitations.count).to eq(5)
+    end
+
+    it "sends an email notification to the user" do
+      expect(enqueued_jobs.size).to eq(1)
+      expect(enqueued_jobs.first["job_class"]).to eq("ActionMailer::MailDeliveryJob")
+      args = enqueued_jobs.first['arguments']
+      expect(args[0]).to eq("NotificationMailer")
+      expect(args[1]).to eq("new_invitations_available")
+      expect(args[3]["params"]["user"]["_aj_globalid"]).to eq("gid://akkounts/User/1")
+    end
+  end
+
+  describe "#call with notification disabled" do
+    before do
+      CreateInvitations.call(user: user, amount: 3, notify: false)
+    end
+
+    after(:each) { clear_enqueued_jobs }
+
+    it "does not send an email notification to the user" do
+      expect(enqueued_jobs.size).to eq(0)
+    end
+  end
+end