Add spec for message as_json containing call_logs

twilio/spec/models/message_spec.rb

@@ -0,0 +1,9 @@
+require 'rails_helper'
+
+RSpec.describe Message, :type => :model do
+  it "includes call_logs in json output" do
+    message = generate_message(true)
+    message.call_logs.create(number: 'blah')
+    expect(message.as_json).to include("call_logs")
+  end
+end