Transfers: result includes also winning solemnities

This makes the transfer logic completely encapsulated in Transfers and
celebration precedence logic in Calendar#celebrations_for doesn't
interfere with it anymore.
This is the ultimate fix to the solemnity loss and duplication bug (#80).

lib/calendarium-romanum/transfers.rb

@@ -1,6 +1,6 @@
 module CalendariumRomanum
 
-  # Internal {Calendar} component.
+  # {Calendar} component.
   # Resolves transfers of conflicting solemnities.
   #
   # For any day {Temporale} has a {Celebration}.
@@ -12,22 +12,31 @@ module CalendariumRomanum
   # one is celebrated on the given day and the less lucky one
   # must be transferred to another day.
   # However, not all days are valid as targets of solemnity transfer.
-  #
-  # @api private
+  # This class handles the logic of transferring impeded solemnities
+  # to suitable dates.
   class Transfers
     # @param temporale [Temporale]
     # @param sanctorale [Sanctorale]
+    # @api private
     def initialize(temporale, sanctorale)
       @temporale = temporale
       @sanctorale = sanctorale
     end
 
+    # Resolves any conflict between temporale and sanctorale solemnities
+    # by deciding which of the conflicting solemnities is to take the original
+    # date, which is to be transferred, and specifying a date for both of them
+    # in the resulting Hash.
+    #
+    # @param temporale [Temporale]
+    # @param sanctorale [Sanctorale]
     # @return [Hash<Date=>Celebration>]
     def self.call(temporale, sanctorale)
       new(temporale, sanctorale).call
     end
 
     # @return [Hash<Date=>Celebration>]
+    # @api private
     def call
       @transferred = {}
 
@@ -42,7 +51,7 @@ def call
         sc = @sanctorale[date].first
         next unless sc && sc.solemnity?
 
-        loser = [sc, tc].sort_by(&:rank).first
+        loser, winner = [sc, tc].sort_by(&:rank)
 
         transfer_to =
           if loser.symbol == :annunciation && in_holy_week?(date)
@@ -52,6 +61,8 @@ def call
             free_day_closest_to(date)
           end
         @transferred[transfer_to] = loser
+        # primary celebrations have noone to be beaten by, no need to harden their dates
+        @transferred[date] = winner unless winner.rank == Ranks::PRIMARY
       end
 
       @transferred

spec/calendar_spec.rb

@@ -500,59 +500,6 @@
         end
       end
 
-      describe 'effect of transfers' do
-        let(:year) { 2032 } # year with an interesting solemnity collision
-        let(:temporale) { CR::Temporale.new year }
-        let(:sanctorale) { CR::Data::GENERAL_ROMAN_ENGLISH.load }
-        let(:calendar) { described_class.new(temporale, sanctorale, transfers: transfers) }
-        let(:date) { Date.new 2033, 6, 24 }
-
-        before :each do
-          # make sure
-          all_celebrations = sanctorale[date] + [temporale[date]]
-
-          expect(all_celebrations)
-            .to all(be_solemnity)
-          expect(all_celebrations.collect(&:rank).uniq.size).to eq 1 # same rank
-        end
-
-        describe 'collision not resolved' do
-          let(:transfers) { proc { {} } } # no solution, just an empty Hash
-
-          it 'temporale solemnity wins, sanctorale one is lost' do
-            expect(calendar[date].celebrations)
-              .to eq [temporale[date]]
-
-            expect(calendar[date + 1].celebrations)
-              .not_to eq sanctorale[date]
-            expect(calendar[date - 1].celebrations)
-              .not_to eq sanctorale[date]
-          end
-        end
-
-        describe 'sanctorale solemnity transferred' do
-          let(:transfers) { proc { {(date + 1) => sanctorale[date].first} } }
-
-          it 'works as expected' do
-            expect(calendar[date].celebrations)
-              .to eq [temporale[date]]
-            expect(calendar[date + 1].celebrations)
-              .to eq sanctorale[date]
-          end
-        end
-
-        describe 'temporale solemnity transferred' do
-          let(:transfers) { proc { {(date + 1) => temporale[date]} } }
-
-          it 'works as expected' do
-            expect(calendar[date].celebrations)
-              .to eq sanctorale[date]
-            expect(calendar[date + 1].celebrations)
-              .to eq [temporale[date]]
-          end
-        end
-      end
-
       it 'transfer of suppressed Annunciation (real world example)' do
         c = described_class.new 2015, s
 

spec/transfers_spec.rb

@@ -112,7 +112,7 @@ def date_set_temporale_impeded(date)
       let(:sanctorale_solemnity) { lower_solemnity }
 
       it 'wins' do
-        expect(transfers.call).to eq({(date + 1) => sanctorale_solemnity})
+        expect(transfers.call).to eq({date => temporale_solemnity, (date + 1) => sanctorale_solemnity})
       end
     end
 
@@ -121,7 +121,7 @@ def date_set_temporale_impeded(date)
       let(:sanctorale_solemnity) { higher_solemnity }
 
       it 'wins' do
-        expect(transfers.call).to eq({(date + 1) => temporale_solemnity})
+        expect(transfers.call).to eq({date => sanctorale_solemnity, (date + 1) => temporale_solemnity})
       end
     end
 
@@ -130,7 +130,7 @@ def date_set_temporale_impeded(date)
       let(:sanctorale_solemnity) { CR::Celebration.new('s', rank: CR::Ranks::SOLEMNITY_GENERAL) }
 
       it 'temporale wins' do
-        expect(transfers.call).to eq({(date + 1) => sanctorale_solemnity})
+        expect(transfers.call).to eq({date => temporale_solemnity, (date + 1) => sanctorale_solemnity})
       end
     end
   end
@@ -150,7 +150,7 @@ def date_set_temporale_impeded(date)
         date_set(date + 1, sanctorale_cel: celebration_in_the_way)
         date_set_free(date - 1)
 
-        # date+1 was impeded by celebration_in_the_way
+        # date+1 was impeded by celebration_in_the_way, transferring backwards
         expect(transfers.call).to eq({(date - 1) => solemnity})
       end
     end