Add #ceremony_country_in_the_commonwealth?

I want the `MarriageAbroadCalculator` to encapsulate all the logic
required by the flow and views. Delegating to the
`MarriageAbroadDataQuery` for this method is a step toward that goal.

Interestingly we have another, different, concept of Commonwealth
countries in `RegistrationsDataQuery`. I've made a separate note to
investigate that.

lib/smart_answer/calculators/marriage_abroad_calculator.rb

@@ -151,5 +151,9 @@ def opposite_sex_no_marriage_related_consular_services_in_ceremony_country?
     def opposite_sex_affirmation_country?
       @data_query.os_affirmation_countries?(ceremony_country)
     end
+
+    def ceremony_country_in_the_commonwealth?
+      @data_query.commonwealth_country?(ceremony_country)
+    end
   end
 end

lib/smart_answer_flows/marriage-abroad.rb

@@ -211,7 +211,7 @@ def define
               :outcome_os_consular_cni
             elsif calculator.opposite_sex_affirmation_country?
               :outcome_os_affirmation
-            elsif data_query.commonwealth_country?(calculator.ceremony_country) ||
+            elsif calculator.ceremony_country_in_the_commonwealth? ||
                 calculator.ceremony_country == 'zimbabwe'
               :outcome_os_commonwealth
             elsif data_query.british_overseas_territories?(calculator.ceremony_country)

test/unit/calculators/marriage_abroad_calculator_test.rb

@@ -524,6 +524,17 @@ class MarriageAbroadCalculatorTest < ActiveSupport::TestCase
           assert_equal 'opposite-sex-affirmation-country', calculator.opposite_sex_affirmation_country?
         end
       end
+
+      context '#ceremony_country_in_the_commonwealth' do
+        should 'delegate to the data query' do
+          data_query = stub.quacks_like(MarriageAbroadDataQuery.new)
+          data_query.stubs(:commonwealth_country?).with('ceremony-country').returns('commonwealth-country')
+          calculator = MarriageAbroadCalculator.new(data_query: data_query)
+          calculator.ceremony_country = 'ceremony-country'
+
+          assert_equal 'commonwealth-country', calculator.ceremony_country_in_the_commonwealth?
+        end
+      end
     end
   end
 end