@Test
 public void fail_on_invalid_option() {
   try {
     validation.validate("abc", newArrayList("a", "b", "c"));
     fail();
   } catch (Exception e) {
     assertThat(e).isInstanceOf(BadRequestException.class);
     BadRequestException badRequestException = (BadRequestException) e;
     assertThat(badRequestException.l10nParams().toArray()[0]).isEqualTo("abc");
     assertThat(badRequestException.l10nParams().toArray()[1]).isEqualTo("a, b, c");
   }
 }
 @Test
 public void not_fail_on_valid_option() {
   validation.validate("a", newArrayList("a", "b", "c"));
 }
 @Test
 public void key() {
   assertThat(validation.key()).isEqualTo("SINGLE_SELECT_LIST");
 }