Add use_cbor_discrimination tests.

spec/cbor_discrimination.cr

@@ -0,0 +1,65 @@
+require "./spec_helper"
+
+class Game
+  include CBOR::Serializable
+
+  abstract class Player
+    include CBOR::Serializable
+
+    @[CBOR::Field(key: "hp")]
+    property health_points : Int32 = 100
+
+    @[CBOR::Field(key: "dp")]
+    property defense_points : Int32 = 5
+
+    use_cbor_discriminator "type", {
+        magician: Magician,
+        warrior: Warrior
+      }
+    def initialize
+    end
+  end
+
+  class Magician < Player
+    property wand_level : Int32 = 1
+    def initialize
+      @type = "magician"
+    end
+  end
+
+  class Warrior < Player
+    def initialize
+      @defense_points = 20
+      @type = "warrior"
+    end
+  end
+
+  property players : Array(Magician | Warrior)
+
+  def initialize
+    @players = [] of (Magician | Warrior)
+  end
+end
+
+describe CBOR do
+  describe "Complex object representations" do
+    it "Game#to_cbor with use_cbor_discriminator" do
+      game = Game.new
+      magician = Game::Magician.new
+      magician.wand_level = 5
+      game.players << magician
+      game.players << Game::Warrior.new
+      game.to_cbor.hexstring.should eq "a167706c617965727382a46268701864626470056a77616e645f6c6576656c056474797065686d6167696369616ea362687018646264701464747970656777617272696f72"
+    end
+
+    it "Game#from_cbor with use_cbor_discriminator" do
+      game = Game.new
+      magician = Game::Magician.new
+      magician.wand_level = 5
+      game.players << magician
+      game.players << Game::Warrior.new
+      new_game = Game.from_cbor game.to_cbor
+      new_game.to_cbor.hexstring.should eq "a167706c617965727382a46268701864626470056a77616e645f6c6576656c056474797065686d6167696369616ea362687018646264701464747970656777617272696f72"
+    end
+  end
+end