Port existing test from rspec to minitest

.github/workflows/ci.yml

@@ -23,4 +23,4 @@ jobs:
           bundler-cache: true
 
       - name: Run tests
-        run: bundle exec rake spec
+        run: bundle exec rake test

.rubocop.yml

@@ -1,19 +1,12 @@
 plugins:
   - rubocop-rake
-require:
-  - rubocop-rspec
+  - rubocop-minitest
 
 AllCops:
   NewCops: disable
 
 Metrics/MethodLength:
-  Max: 20
+  Max: 30
 
-Capybara/RSpec/PredicateMatcher:
-  Enabled: false
-
-RSpec/ExampleLength:
-  Max: 15
-
-RSpec/MultipleExpectations:
-  Max: 5
+Metrics/AbcSize:
+  Max: 25

Gemfile

@@ -11,8 +11,8 @@ gem 'pry'
 gem 'rake', '~> 13.0'
 
 gem 'mail'
-gem 'rspec', '~> 3.0'
+gem 'minitest', '~> 5.0'
 
 gem 'rubocop', '~> 1.21'
+gem 'rubocop-minitest', '~> 0.35', require: false
 gem 'rubocop-rake', '~> 0.6', require: false
-gem 'rubocop-rspec', '~> 2.5', require: false

Rakefile

@@ -1,12 +1,16 @@
 # frozen_string_literal: true
 
 require 'bundler/gem_tasks'
-require 'rspec/core/rake_task'
+require 'rake/testtask'
 
-RSpec::Core::RakeTask.new(:spec)
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'test'
+  t.libs << 'lib'
+  t.test_files = FileList['test/**/*_test.rb']
+end
 
 require 'rubocop/rake_task'
 
 RuboCop::RakeTask.new
 
-task default: %i[spec rubocop]
+task default: %i[test rubocop]

lib/safety_mailer/safety_mailer.rb

@@ -91,7 +91,7 @@ def prepare_sendgrid_delivery(addresses)
     end
 
     def log(msg)
-      Rails.logger.warn(msg) if defined?(Rails)
+      Rails.logger.warn(msg) if defined?(Rails) && Rails.respond_to?(:logger)
     end
   end
 end

test/safety_mailer/carrier_test.rb

@@ -0,0 +1,112 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+require 'mail'
+require 'json'
+
+module SafetyMailer
+  class CarrierTest < Minitest::Test
+    class MockDeliveryMethod
+      attr_reader :delivered_mail, :called
+
+      def initialize
+        @delivered_mail = nil
+        @called = false
+      end
+
+      def deliver!(mail)
+        @delivered_mail = mail
+        @called = true
+      end
+    end
+
+    def test_no_recipient_is_whitelisted_suppresses_delivery
+      mock_delivery = MockDeliveryMethod.new
+      Mail::SMTP.stub(:new, mock_delivery) do
+        message = Mail.new do
+          from    'safety@example.com'
+          to      'mailer@example.com, pop@oozou.com'
+          subject 'Angry Birds Star Wars'
+          body    'Lorem ipsum dolor sit amet'
+        end
+
+        SafetyMailer::Carrier.new({ allowed_matchers: [/@unrelated\.com$/] }).deliver!(message)
+
+        refute mock_delivery.called, 'Expected delivery to be suppressed'
+      end
+    end
+
+    def test_allows_mail_to_go_only_to_whitelisted_recipients
+      mock_delivery = MockDeliveryMethod.new
+
+      Mail::SMTP.stub(:new, mock_delivery) do
+        message = Mail.new do
+          from    'safety@example.com'
+          to      'mailer@example.com, pop@oozou.com'
+          subject 'Angry Birds Star Wars'
+          body    'Lorem ipsum dolor sit amet'
+        end
+
+        SafetyMailer::Carrier.new({ allowed_matchers: [/@oozou\.com$/] }).deliver!(message)
+
+        assert mock_delivery.called, 'Expected delivery to be called'
+        refute_includes mock_delivery.delivered_mail.to, 'mailer@example.com'
+        assert_includes mock_delivery.delivered_mail.to, 'pop@oozou.com'
+      end
+    end
+
+    def test_ignores_sendgrid_headers_strips_out_unsafe_recipients
+      mock_delivery = MockDeliveryMethod.new
+
+      Mail::SMTP.stub(:new, mock_delivery) do
+        message = Mail.new do
+          from    'safety@example.com'
+          to      'mailer@example.com, pop@oozou.com'
+          subject 'Angry Birds Star Wars'
+          body    'Lorem ipsum dolor sit amet'
+        end
+        message['X-SMTPAPI'] = '{}'
+
+        SafetyMailer::Carrier.new(allowed_matchers: [/@oozou\.com$/]).deliver!(message)
+
+        assert mock_delivery.called, 'Expected delivery to be called'
+        refute_includes mock_delivery.delivered_mail.to, 'mailer@example.com'
+        assert_includes mock_delivery.delivered_mail.to, 'pop@oozou.com'
+      end
+    end
+
+    def test_strips_out_unsafe_recipients_and_corresponding_substitutions
+      mock_delivery = MockDeliveryMethod.new
+
+      Mail::SMTP.stub(:new, mock_delivery) do
+        message = Mail.new do
+          from    'safety@example.com'
+          subject 'Lunch Order'
+          body    'You like -food-'
+        end
+        sendgrid = {
+          'to' => ['mailer@example.com', 'pop@oozou.com'],
+          'sub' => { '-food-' => %w[bagels sushi] }
+        }
+        message['X-SMTPAPI'] = JSON.generate(sendgrid)
+
+        SafetyMailer::Carrier.new(allowed_matchers: [/@oozou\.com$/]).deliver!(message)
+
+        assert mock_delivery.called, 'Expected delivery to be called'
+        parsed = JSON.parse(mock_delivery.delivered_mail['X-SMTPAPI'].value)
+        recipients = parsed['to']
+        refute_includes recipients, 'mailer@example.com'
+        assert_includes recipients, 'pop@oozou.com'
+
+        substitutions = parsed['sub']
+        refute_includes substitutions['-food-'], 'bagels'
+        assert_includes substitutions['-food-'], 'sushi'
+      end
+    end
+
+    def test_allows_initialization_with_custom_delivery_method
+      carrier = SafetyMailer::Carrier.new(delivery_method: :faker)
+      assert_instance_of SafetyMailer::Carrier, carrier
+    end
+  end
+end

test/safety_mailer_test.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class SafetyMailerTest < Minitest::Test
+  def test_has_version_number
+    refute_nil SafetyMailer::VERSION
+  end
+end

test/test_helper.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'minitest/autorun'
+require 'safety_mailer'
+require 'pry'
+require 'support/fake_mailer'
+require 'action_mailer'
+
+ActionMailer::Base.add_delivery_method :faker, FakeMailer