@Test
 public void ball_rolls_for_a_random_time_between_30_and_40_seconds() throws Exception {
   when(rng.generate(30, 40)).thenReturn(33);
   rt.roll();
   timer.moveTime(33001);
   assertFalse(rt.isBallRolling());
 }
 @Test
 public void ball_starts_rolling_when_all_players_signal_done() throws Exception {
   // arrange
   Player p2 = new Player();
   Player p3 = new Player();
   rt.placeBet(p, Field.forNumber(1), 10);
   rt.placeBet(p2, Field.forNumber(2), 10);
   rt.placeBet(p3, Field.forNumber(3), 10);
   // act
   rt.done(p);
   rt.done(p2);
   rt.done(p3);
   assertTrue(rt.isBallRolling());
 }