flesh out Player tests

test/elo.rb

@@ -74,10 +74,66 @@
   end
 
   describe Elo::Player do
-    it "must be initialized with an Elo object" do
-      expect { Elo::Player.new }.must_raise ArgumentError
-      expect { Elo::Player.new(1234) }.must_raise ArgumentError
-      expect(Elo::Player.new(Elo.new)).must_be_kind_of Elo::Player
+    it "has sensible defaults" do
+      expect(Elo::Player.new).must_be_kind_of Elo::Player
+    end
+
+    it "may be initialized with an Elo object" do
+      expect(Elo::Player.new(elo: Elo.new)).must_be_kind_of Elo::Player
+    end
+
+    it "is Comparable, based on Elo rating" do
+      a = Elo::Player.new
+      b = Elo::Player.new
+
+      expect(a <=> b).must_equal 0
+      a.rating = 2 * b.rating
+      expect(a <=> b).must_equal 1
+      b.rating = a.rating + 1
+      expect(a <=> b).must_equal(-1)
+
+      a.rating = b.rating
+      expect(a == b).must_equal true
+      expect(a == a).must_equal true
+
+      a.rating = b.rating + 1
+      expect(a > b).must_equal true
+    end
+
+    it "can initialize a pool of players" do
+      pool = Elo::Player.init_pool(99)
+      expect(pool).must_be_kind_of Array
+      pool.each { |player| player.rating = rand(2000) }
+      sorted = pool.sort # sorts on rating because of <=> and Comparable
+      expect(sorted.first.rating).must_be :<, sorted.last.rating
+    end
+
+    it "updates both self and opponent with a match outcome" do
+      a = Elo::Player.new
+      b = Elo::Player.new
+
+      # 5 wins for _a_
+      5.times { a.update(b, 1) }
+
+      expect(a > b).must_equal true
+
+      a_rating, b_rating = a.rating, b.rating
+
+      # a draw, _a_'s rating goes down, _b_'s goes up
+      a.update(b, 0.5)
+      expect(a.rating).must_be :<, a_rating
+      expect(b.rating).must_be :>, b_rating
+    end
+
+    it "can perform skill-based match simulations" do
+      a = Elo::Player.new(skill: 0.95)
+      b = Elo::Player.new(skill: 0.3)
+
+      expect(a == b).must_equal true   # ratings are the same
+
+      # 99 matches
+      99.times { a.simulate(b) }
+      expect(a > b).must_equal true    # a's rating should increase
     end
   end
 end