@Test
void calculateUsage() {

    // 1 cpu, cpu uses 100ns, elapsed 100ns
    assertThat(stat.usage(200L, 100L, 200L, 100L, 1))
            .isEqualTo(1);
    // 2 cpus, cpu uses 100ns, elapsed 200ns
    assertThat(stat.usage(300L, 100L, 200L, 100L, 2))
            .isEqualTo(0.25);
}