Add service to create a mail method

This will make loading sample data into staging environments easier.

app/services/create_mail_method.rb

@@ -0,0 +1,34 @@
+# Configures Rails to use the specified mail settings. It does so creating
+# a Spree::MailMethod and applying its configuration.
+class CreateMailMethod
+  # Constructor
+  #
+  # @param attributes [Hash] MailMethod attributes
+  def initialize(attributes)
+    @attributes = attributes
+  end
+
+  def call
+    persist_attributes
+    initialize_mail_settings
+  end
+
+  private
+
+  attr_reader :attributes
+
+  # Updates the created mail method's attributes with the ones specified
+  def persist_attributes
+    mail_method.update_attributes(attributes)
+  end
+
+  # Creates a new Spree::MailMethod for the current environment
+  def mail_method
+    Spree::MailMethod.create(environment: attributes[:environment])
+  end
+
+  # Makes Spree apply the specified mail settings
+  def initialize_mail_settings
+    Spree::Core::MailSettings.init
+  end
+end

spec/services/create_mail_method_spec.rb

@@ -0,0 +1,41 @@
+require 'spec_helper'
+
+describe CreateMailMethod do
+  describe '#call' do
+    let(:mail_method) { Spree::MailMethod.create(environment: 'test') }
+    let(:mail_settings) { instance_double(Spree::Core::MailSettings) }
+    let(:attributes) do
+      { preferred_smtp_username: "smtp_username", environment: "test" }
+    end
+
+    before do
+      allow(Spree::MailMethod)
+        .to receive(:create).with(environment: 'test').and_return(mail_method)
+      allow(Spree::Core::MailSettings).to receive(:init) { mail_settings }
+    end
+
+    it 'creates a new MailMethod' do
+      described_class.new(attributes).call
+
+      expect(Spree::MailMethod)
+        .to have_received(:create).with(environment: 'test') { mail_method }
+    end
+
+    it 'updates the MailMethod' do
+      expect(mail_method)
+        .to(receive(:update_attributes)).with(attributes) { mail_method }
+
+      described_class.new(attributes).call
+    end
+
+    it 'updates the mail method attributes' do
+      described_class.new(attributes).call
+      expect(mail_method.preferred_smtp_username).to eq('smtp_username')
+    end
+
+    it 'initializes the mail settings' do
+      described_class.new(attributes).call
+      expect(Spree::Core::MailSettings).to have_received(:init)
+    end
+  end
+end