diff --git a/spec/cbor_spec.cr b/spec/cbor_spec.cr
index 56eaa99..c1708c4 100644
--- a/spec/cbor_spec.cr
+++ b/spec/cbor_spec.cr
@@ -24,26 +24,101 @@ class House
 end
 
 class Person
-	include CBOR::Serializable
-	include CBOR::Serializable::Unmapped
+  include CBOR::Serializable
+  include CBOR::Serializable::Unmapped
 
-	property name : String?
-	def initialize(@name = nil)
-	end
+  property name : String?
+  def initialize(@name = nil)
+  end
+end
+
+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 "basics: to_cbor" do
+    it "empty array" do
+      empty_array_cbor = [] of Nil
+      empty_array_cbor.to_cbor.hexstring.should eq "80"
+    end
+
     it "array - strings" do
       ["a", "b", "c"].to_cbor.hexstring.should eq "83616161626163"
     end
-    it "array - " do
-      ["a", "b", "c"].to_cbor.hexstring.should eq "83616161626163"
+
+    it "empty hash" do
+      empty = {} of Nil => Nil
+      cbor_stuff = empty.to_cbor
+      cbor_stuff.hexstring.should eq "a0"
     end
+
     it "hash" do
       {"a" => 10, "b" => true, "c" => nil}.to_cbor.hexstring.should eq "a361610a6162f56163f6"
     end
+
+    it "union String | Int32" do
+      value = (String | Int32).from_cbor(30.to_cbor).to_cbor
+      value.hexstring.should eq "181e"
+    end
+    it "union (String | Int32)" do
+      value = (String | Int32).from_cbor("blah".to_cbor).to_cbor
+      value.hexstring.should eq "64626c6168"
+    end
+    it "union (Bool | Int32)" do
+      value = (Bool | Int32).from_cbor(30.to_cbor).to_cbor
+      value.hexstring.should eq "181e"
+    end
+    it "union (Bool | Int32)" do
+      value = (Bool | Int32).from_cbor(false.to_cbor).to_cbor
+      value.hexstring.should eq "f4"
+    end
+    it "union (String | Bool | Int32)" do
+      value = (String | Bool | Int32).from_cbor("hello".to_cbor).to_cbor
+      value.hexstring.should eq "6568656c6c6f"
+    end
+    it "union (String | Nil | Int32)" do
+      value = (String | Nil | Int32).from_cbor(nil.to_cbor).to_cbor
+      value.hexstring.should eq "f6"
+    end
   end
 
   describe "Time" do
@@ -72,6 +147,20 @@ describe CBOR do
 
 
   describe "CBOR library annotations and features" do
+    it "House#to_cbor with CBOR::Field annotations" do
+      house = House.new "my address"
+      house.location = Location.new 1.1, 1.2
+      house.to_cbor.hexstring.should eq "a267616464726573736a6d792061646472657373686c6f636174696f6ea2636c6174fb3ff199999999999a636c6e67fb3ff3333333333333"
+    end
+
+    it "House#from_cbor with CBOR::Field annotations" do
+      other_house = House.new "my address"
+      other_house.location = Location.new 1.1, 1.2
+
+      house = House.from_cbor other_house.to_cbor
+      house.to_cbor.hexstring.should eq "a267616464726573736a6d792061646472657373686c6f636174696f6ea2636c6174fb3ff199999999999a636c6e67fb3ff3333333333333"
+    end
+
     it "Person#from_cbor with unmapped values" do
       h = Hash(String | Int32, String | Int32).new
       h["name"] = "Alice"
@@ -118,4 +207,26 @@ describe CBOR do
       cbor_any_hash.to_cbor.hexstring.should eq "a3646e616d6565416c69636563616765181e6473697a6518a0"
     end
   end
+
+  # db[i]?.should be_nil
+  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