Define a WheelSwap class that randomly swaps one guest from each table

app/services/tables/wheel_swap.rb

@@ -10,7 +10,12 @@ module Tables
     end
 
     def call
-      @initial_solution.deep_dup
+      new_solution = @initial_solution.deep_dup
+      
+      selected_guests = new_solution.tables.map(&:pop).cycle.tap(&:next)
+      new_solution.tables.each { |table| table << selected_guests.next }
+
+      new_solution
     end
   end
 end

config/initializers/ruby_extensions.rb

@@ -10,4 +10,10 @@ class Set
   def to_table
     Tables::Table.new(self)
   end
+
+  def pop
+    element = self.to_a.sample
+    self.delete(element)
+    element
+  end
 end

spec/services/tables/wheel_swap_spec.rb

@@ -15,6 +15,13 @@ module Tables
         result = described_class.new(initial_solution).call
         
         expect(result.tables.size).to eq(3)
+        expect(result.tables.map(&:size)).to all(eq(3))
+
+        expect(result.tables).not_to include(initial_solution.tables[0])
+        expect(result.tables).not_to include(initial_solution.tables[1])
+        expect(result.tables).not_to include(initial_solution.tables[2])
+
+        expect(result.tables.map(&:to_a).flatten).to contain_exactly(*(:a..:i).to_a)
       end
     end
   end