public GearAssert assertGear(String id) {
    assertNotNull(id);

    for (IGear gear : gearGroup.getGears()) {
      if (id.equals(gear.getId())) {
        return new GearAssert(gear);
      }
    }
    fail("gear group " + gearGroup.getName() + " does not contain a gear with id " + id);
    return null;
  }
 public GearAssert hasId() {
   assertThat(gear.getId()).isNotNull().isNotEmpty();
   return this;
 }
 public GearAssert hasId(String id) {
   assertNotNull(id);
   assertEquals(id, gear.getId());
   return this;
 }