### Question:
InMemoryMetricExporter implements MetricExporter { @Override public CompletableResultCode flush() { return CompletableResultCode.ofSuccess(); } private  InMemoryMetricExporter(); static InMemoryMetricExporter create(); List<MetricData> getFinishedMetricItems(); void reset(); @Override CompletableResultCode export(Collection<MetricData> metrics); @Override CompletableResultCode flush(); @Override void shutdown();  }### Answer:
@Test void test_flush() { assertThat(exporter.flush().isSuccess()).isTrue(); }