Refactor/Move Method: moved a computation to a more sensible place.

lib/location.rb

@@ -22,10 +22,18 @@ def initialize(coordinates:, direction:)
   end
 
   def forwards
-    Location.new(
-      coordinates: Coordinates.new(x: coordinates.x, y: (coordinates.y + 1)),
-      direction: direction
-    )
+    case direction
+    when 'N'
+      Location.new(
+        coordinates: Coordinates.new(x: coordinates.x, y: (coordinates.y + 1)),
+        direction: direction
+      )
+    when 'S'
+      Location.new(
+        coordinates: Coordinates.new(x: coordinates.x, y: (coordinates.y - 1)),
+        direction: direction
+      )
+    end
   end
 
   def rotate_left

lib/map.rb

@@ -16,15 +16,8 @@ def next_location_forwards(location:)
         direction: location.direction
       )
     when 'S'
-      new_location = Location.new(
-        coordinates: Coordinates.new(x: location.coordinates.x, y: (location.coordinates.y - 1)),
-        direction: location.direction
-      )
-      if located_at_south_pole? new_location.coordinates
-        Location.new(coordinates: Coordinates.new(x: 18, y: -8), direction: 'N')
-      else
-        new_location
-      end
+      new_location = location.forwards
+      corrected_for_south_pole(new_location)
     when 'W'
       next_x = at_left_hand_edge?(location.coordinates) ? @x_domain.end : location.coordinates.x - 1
       Location.new(
@@ -65,6 +58,14 @@ def next_location_backwards(location:)
 
   private
 
+  def corrected_for_south_pole(location)
+    if located_at_south_pole? location.coordinates
+      Location.new(coordinates: Coordinates.new(x: 18, y: -8), direction: 'N')
+    else
+      location
+    end
+  end
+
   def corrected_for_north_pole(location)
     if at_north_pole? location.coordinates
       Location.south_facing(coordinates: Coordinates.new(x: location.coordinates.x + 18, y: 8))