@Test public void builderPopExplodesIfCountIsTooLarge() {

  History.Builder builder = History.emptyBuilder();
  builder.push(ABLE);
  builder.push(BAKER);
  builder.push(CHARLIE);
  try {
    builder.pop(4);
    fail("Count is too large, should have thrown");
  } catch (IllegalArgumentException ignored) {
    // Success!
  }
}