@Test
    void test_routing_with_multiple_clusters() {
        VespaModel model = createDualContentCluster();
        Routing routing = model.getRouting();
        assertNotNull(routing);
        assertEquals("[]", routing.getErrors().toString());
        assertEquals(1, routing.getProtocols().size());
        DocumentProtocol protocol = (DocumentProtocol) routing.getProtocols().get(0);
        RoutingTableSpec spec = protocol.getRoutingTableSpec();
        assertEquals(3, spec.getNumHops());
        assertEquals("docproc/cluster.bar_c.indexing/chain.indexing", spec.getHop(0).getName());
        assertEquals("docproc/cluster.foo_c.indexing/chain.indexing", spec.getHop(1).getName());
        assertEquals("indexing", spec.getHop(2).getName());

        assertEquals(10, spec.getNumRoutes());
        assertRoute(spec.getRoute(0), "bar_c", "[MessageType:bar_c]");
        assertRoute(spec.getRoute(1), "bar_c-direct", "[Content:cluster=bar_c]");
        assertRoute(spec.getRoute(2), "bar_c-index", "docproc/cluster.bar_c.indexing/chain.indexing", "[Content:cluster=bar_c]");
        assertRoute(spec.getRoute(3), "default", "indexing");
        assertRoute(spec.getRoute(4), "default-get", "indexing");
        assertRoute(spec.getRoute(5), "foo_c", "[MessageType:foo_c]");
        assertRoute(spec.getRoute(6), "foo_c-direct", "[Content:cluster=foo_c]");
        assertRoute(spec.getRoute(7), "foo_c-index", "docproc/cluster.foo_c.indexing/chain.indexing", "[Content:cluster=foo_c]");
        assertRoute(spec.getRoute(8), "storage/cluster.bar_c", "route:bar_c");
        assertRoute(spec.getRoute(9), "storage/cluster.foo_c", "route:foo_c");
    }
Here there is no good choice.
config-model/src/test/java/com/yahoo/vespa/model/content/ContentClusterTest.java