fail("Expected IllegalArgumentException");
    } catch (IllegalArgumentException expected) {
      // expected
    }
  }

  public static void hashtableTestHelper(ImmutableList<Integer> sizes) {
    for (int size : sizes) {
      Builder<Integer, Integer> builder = ImmutableMap.builderWithExpectedSize(size);
      for (int i = 0; i < size; i++) {
        Integer integer = i;
        builder.put(integer, integer);
      }