add player rating to the db

main-server/spec/models/user_spec.rb

@@ -40,6 +40,19 @@ RSpec.describe User, type: :model do
     end
   end
 
+  describe "rating" do
+    it "defaults to the neutral initial value of 100" do
+      expect(User.create!(valid_attributes).rating).to eq(100)
+    end
+
+    it "requires a rating" do
+      user = User.new(valid_attributes)
+      user.rating = nil
+      expect(user).not_to be_valid
+      expect(user.errors[:rating]).to be_present
+    end
+  end
+
   describe "nickname normalization" do
     it "strips surrounding whitespace" do
       user = User.create!(valid_attributes.merge(nickname: "  player_one  "))