@Test
    public void testDown() throws Exception {
        test = new DistributionTestFactory("down")
                .setUpStates("u")
                .setClusterState(new ClusterState(
                        "distributor:10 .4.s:m .5.s:m .6.s:d .7.s:d .8.s:r .9.s:r"));
        for (BucketId bucket : getTestBuckets()) {
            assertTrue(test.recordResult(bucket).assertNodeCount(1).getNodes().get(0) < 4);
        }
    }
Build a set of buckets to test that should represent the entire bucket space well.
vdslib/src/test/java/com/yahoo/vdslib/distribution/DistributionTestCase.java