@Test
    public void metrics_are_not_retrieved_until_first_request() {
        assertEquals(0, nodeMetricsClient.snapshotsRetrieved());
    }
Two optimizations worth noting:
<p>
1. Using a ClassRule for the wire mocking means it is reused between test methods.
2. Configuring stubs on the rule is faster than using the static WireMock.stubFor method.

@author gjoranv
metrics-proxy/src/test/java/ai/vespa/metricsproxy/http/application/NodeMetricsClientTest.java