@Test
  public void noValidTicket() {
    EventOrganizer eventOrganizer = new EventOrganizer();
    Event gizmoEvent = Fixtures.createEvent("Gizmo");

    assertFalse(eventOrganizer.hasValidTicket("Joe", gizmoEvent));
  }
  @Test
  public void joeBuysStandardTicketForGizmoEvent() {
    EventOrganizer eventOrganizer = new EventOrganizer();
    Event gizmoEvent = Fixtures.createEvent("Gizmo");
    TicketType standardTicketType = Fixtures.createTicketType("Standard");

    eventOrganizer.buyTicket(gizmoEvent, "Joe", standardTicketType);
    assertTrue(eventOrganizer.hasValidTicket("Joe", gizmoEvent));
  }