@Test
public void shouldReadLongValue() {

    AtomicLong value = new AtomicLong(0);
    observer.onLongValue("test", 11L, value::set);
    assertThat(value.get()).isEqualTo(11L);
    writeConfigLine("test = 1337");
    assertThat(value.get()).isEqualTo(1337L);
}