### Question:
MetricService { public void send(final List<Metric> metrics) { Objects.requireNonNull(metrics); mackerel.send(metrics); }  void log(final AvatarType avatarType); List<Metric> collect(); void send(final List<Metric> metrics);  }### Answer:
@Test public void sendTest() { final List<Metric> metrics = List.of( Metric.builder() .name("metric-1") .time(1L) .value(BigDecimal.ONE) .build() ); doNothing().when(mackerel).send(metrics); metricService.send(metrics); verify(mackerel).send(metrics); }