@Test
public void testTrigger() {

  assertThat(trigger("natural", "natural-trigger"), is(Trigger.natural()));
  assertThat(trigger("adhoc", "foo"), is(Trigger.adhoc("foo")));
  assertThat(trigger("backfill", "bar"), is(Trigger.backfill("bar")));
  assertThat(trigger("unknown", "baz"), is(Trigger.unknown("baz")));
}