test for send mail service

app/mailers/send_mail_mailer.rb

@@ -1,4 +1,5 @@
 class SendMailMailer < ApplicationMailer
+  default from: 'support@freesendmailapi.net'
   def send_mail(to_email, subject, email, message)
     @to_email = to_email
     @email = email

spec/services/mail_service_spec.rb

@@ -0,0 +1,104 @@
+require 'rails_helper'
+
+RSpec.describe V1::MailService do
+  include ActiveJob::TestHelper
+  let(:valid_params) do
+    {
+      to_email: 'receive@mail.com',
+      name: 'receive',
+      email: 'sender@mail.com',
+      message: 'message'
+    }
+  end
+
+  let(:invalid_params) do
+    {
+      to_email: '',
+      name: '',
+      email: '',
+      message: ''
+    }
+  end
+
+  after(:each) do
+    ActionMailer::Base.deliveries.clear
+    ActiveJob::Base.queue_adapter = :sidekiq
+  end
+
+  describe '#send_and_redirect' do
+    subject { mail_service.send(:send_and_redirect) }
+
+    context 'when params is valid' do
+      let(:mail_service) { V1::MailService.new(valid_params) }
+
+      it 'return to success_url' do
+        expect(subject).to eq 'http://www.freesendmails.com/test-mail-success'
+      end
+
+      it 'send mail and action mailer size increment 1' do
+        ActiveJob::Base.queue_adapter = :test
+
+        perform_enqueued_jobs do
+          expect do
+            subject
+          end.to change { ActionMailer::Base.deliveries.size }.by(1)
+        end
+      end
+    end
+
+    context 'when params is invalid' do
+      let(:mail_service) { V1::MailService.new(invalid_params) }
+
+      it 'return to error_url' do
+        expect(subject).to eq 'http://www.freesendmails.com/test-mail-error'
+      end
+
+      it 'not send mail and action mailer size is 0' do
+        ActiveJob::Base.queue_adapter = :test
+
+        perform_enqueued_jobs do
+          expect do
+            subject
+          end.to change { ActionMailer::Base.deliveries.size }.by(0)
+        end
+      end
+    end
+  end
+
+  describe '#validation_mail ' do
+    subject { mail_service.send(:validation_mail) }
+    context 'when params is valid' do
+      let(:mail_service) { V1::MailService.new(valid_params) }
+
+      it 'return false' do
+        expect(subject).to eq false
+      end
+    end
+
+    context 'when params is valid' do
+      let(:mail_service) { V1::MailService.new(invalid_params) }
+
+      it 'return false' do
+        expect(subject).to eq true
+      end
+    end
+  end
+
+  describe '#redirect_to_success' do
+    let(:valid_params) do
+      {
+        to_email: 'receive@mail.com',
+        name: 'receive',
+        email: 'sender@mail.com',
+        message: 'message',
+        url_success: 'custom success url'
+      }
+    end
+    let(:mail_service) { V1::MailService.new(valid_params) }
+    subject { mail_service.send(:send_and_redirect) }
+
+    it 'return custom success url' do
+      expect(subject).to eq valid_params[:url_success]
+    end
+  end
+end