  @Test public void backoff() {

    Backo backo = new Backo.Builder().build();

    assertThat(backo.backoff(0)).isEqualTo(100);
    assertThat(backo.backoff(1)).isEqualTo(200);
    assertThat(backo.backoff(2)).isEqualTo(400);
    assertThat(backo.backoff(3)).isEqualTo(800);

    assertThat(backo.backoff(0)).isEqualTo(100);
    assertThat(backo.backoff(1)).isEqualTo(200);
  }