public void assertMembersOf(ClusterSpec requestedCluster, Collection<HostSpec> hosts) {
        Set<Integer> indices = new HashSet<>();
        for (HostSpec host : hosts) {
            ClusterSpec nodeCluster = host.membership().get().cluster();
            assertTrue(requestedCluster.satisfies(nodeCluster));
            if (requestedCluster.group().isPresent())
                assertEquals(requestedCluster.group(), nodeCluster.group());
            else
                assertEquals(0, nodeCluster.group().get().index());

            indices.add(host.membership().get().index());
        }
        assertEquals("Indexes in " + requestedCluster + " are disjunct", hosts.size(), indices.size());
    }
Assert on the current *non retired* nodes
node-repository/src/test/java/com/yahoo/vespa/hosted/provision/provisioning/ProvisioningTester.java