Add create response for SMS

lib/sms/create_response.rb

@@ -0,0 +1,43 @@
+module SMS
+  class CreateResponse
+    INSTRUCTIONS = {
+      'free'    => 'Reply to this message with your answer',
+      'numeric' => 'Reply with a number from "1" to "10" to this message',
+      'yes_no'  => 'Reply with "1" for YES and "0" for NO to this message'
+    }.freeze
+
+    def self.for(question)
+      new(question).response
+    end
+
+    def initialize(question)
+      @question = question
+    end
+
+    def response
+      return exit_message if question == Question::NoQuestion
+
+      Twilio::TwiML::Response.new do |r|
+        r.Message do |msg|
+          msg.Body message_body
+        end
+      end.to_xml
+    end
+
+    private
+
+    attr_reader :question
+
+    def exit_message
+      Twilio::TwiML::Response.new do |r|
+        r.Message do |msg|
+          msg.Body 'Thanks for your time. Good bye'
+        end
+      end.to_xml
+    end
+
+    def message_body
+      [question.body, INSTRUCTIONS.fetch(question.type)].join("\n\n")
+    end
+  end
+end

spec/lib/sms/create_response_spec.rb

@@ -0,0 +1,60 @@
+require 'rails_helper'
+
+describe SMS::CreateResponse do
+  describe '.for' do
+    subject { described_class.for(question) }
+
+    let(:question_type) { 'free' }
+    let(:question) do
+      build_stubbed(:question, body: 'question?', type: question_type)
+    end
+
+    it 'creates a response with the question body' do
+      expect(content_for('/Response/Message/Body'))
+        .to include('question?')
+    end
+
+    context 'when the question type is "free"' do
+      let(:question_type) { 'free' }
+
+      it 'uses the instruction for free questions' do
+        expect(content_for('/Response/Message/Body'))
+          .to include('Reply to this message with your answer')
+      end
+    end
+
+    context 'when the question type is "numeric"' do
+      let(:question_type) { 'numeric' }
+
+      it 'uses the instruction for numeric questions' do
+        expect(content_for('/Response/Message/Body'))
+          .to include('Reply with a number from "1" to "10" to this message')
+      end
+    end
+
+    context 'when the question type is "yes_no"' do
+      let(:question_type) { 'yes_no' }
+
+      it 'uses the instruction for yes_no questions' do
+        expect(content_for('/Response/Message/Body'))
+          .to include('Reply with "1" for YES and "0" for NO to this message')
+      end
+    end
+
+    context 'when the question is Question::NoQuestion' do
+      let(:question) { Question::NoQuestion }
+
+      it 'responds with a closing message' do
+        expect(content_for('/Response/Message/Body'))
+          .to eq('Thanks for your time. Good bye')
+      end
+    end
+  end
+
+  private
+
+  def content_for(xpath)
+    document = Nokogiri::XML(subject)
+    document.at_xpath(xpath).content
+  end
+end