validate game startable

app/models/game.rb

@@ -1,31 +1,31 @@
 # The game class
 class Game < ActiveRecord::Base
-  has_many :players, :dependent => :destroy
+  has_many :players, dependent: :destroy
   has_many :users, through: :players
   accepts_nested_attributes_for :players
   validates :title, presence: true
 
   def start
     # Save the game to the database
+    return false unless startable?
     save
     # Start the game TODO
   end
 
   def validate_startable
-    @player_count = players.size
+    @player_count = players.count
     errors[:notice] = 'Must be at least 2 players.'  if @player_count < 2
     errors[:players] = 'Must be less than 5 players.'  if @player_count > 4
   end
 
-  def is_startable?
+  def startable?
     @player_count = players.size
     @player_count.between?(2, 4)
   end
 
   def add_player_from_user(user)
-    if can_accomodate(user)
-      Player.create(user: user, game: self)
-    end
+    return false unless can_accomodate(user)
+    self.players.create(user: user)
   end
 
   def can_accomodate(user)

spec/models/game_spec.rb

@@ -42,6 +42,6 @@ RSpec.describe Game, type: :model do
   end
 
   it 'Can not be started if game is invalid' do
-    expect(@game.start).to eq false
+    expect(@game.start).to raise_error
   end
 end