Allow target and local target comparison

This way we'll be able to sort a mixed collection of targets and local
targets.

app/models/sdg/local_target.rb

@@ -17,10 +17,12 @@ class SDG::LocalTarget < ApplicationRecord
 
   belongs_to :target
 
-  def <=>(local_target)
-    return unless local_target.class == self.class
-
-    [target, numeric_subcode] <=> [local_target.target, local_target.numeric_subcode]
+  def <=>(any_target)
+    if any_target.class == self.class
+      [target, numeric_subcode] <=> [any_target.target, any_target.numeric_subcode]
+    elsif any_target.class == target.class
+      -1 * (any_target <=> self)
+    end
   end
 
   protected

app/models/sdg/target.rb

@@ -12,10 +12,12 @@ class SDG::Target < ApplicationRecord
     I18n.t("sdg.goals.goal_#{goal.code}.targets.target_#{code_key}.title")
   end
 
-  def <=>(target)
-    return unless target.class == self.class
-
-    [goal.code, numeric_subcode] <=> [target.goal.code, target.numeric_subcode]
+  def <=>(any_target)
+    if any_target.class == self.class
+      [goal.code, numeric_subcode] <=> [any_target.goal.code, any_target.numeric_subcode]
+    elsif any_target.class.name == "SDG::LocalTarget"
+      [self, -1] <=> [any_target.target, 1]
+    end
   end
 
   def self.[](code)

spec/models/sdg/local_target_spec.rb

@@ -73,5 +73,13 @@ describe SDG::LocalTarget do
       expect(local_target).to be > lesser_local_target
       expect(local_target).to be < greater_local_target
     end
+
+    it "can be compared against global targets" do
+      lesser_target = build(:sdg_target, code: "10.A", goal: SDG::Goal[10])
+      greater_target = build(:sdg_target, code: "11.1", goal: SDG::Goal[11])
+
+      expect(local_target).to be > lesser_target
+      expect(local_target).to be < greater_target
+    end
   end
 end

spec/models/sdg/target_spec.rb

@@ -61,6 +61,32 @@ describe SDG::Target do
       expect(target).to be > lesser_target
       expect(target).to be < greater_target
     end
+
+    context "comparing with a local target" do
+      it "compares using the goal first" do
+        lesser_local_target = build(:sdg_local_target, code: "2.1.1")
+        greater_local_target = build(:sdg_local_target, code: "11.1.2")
+
+        expect(target).to be > lesser_local_target
+        expect(target).to be < greater_local_target
+      end
+
+      it "compares using the target when the goal is the same" do
+        lesser_target = build(:sdg_target, code: "10.2", goal: goal)
+        greater_target = build(:sdg_target, code: "10.A", goal: goal)
+        lesser_local_target = build(:sdg_local_target, code: "10.2.25", target: lesser_target)
+        greater_local_target = build(:sdg_local_target, code: "10.A.1", target: greater_target)
+
+        expect(target).to be > lesser_local_target
+        expect(target).to be < greater_local_target
+      end
+
+      it "is smaller than a local target belonging to it" do
+        local_target = build(:sdg_local_target, target: target, code: "10.19.1")
+
+        expect(target).to be < local_target
+      end
+    end
   end
 
   describe ".[]" do