private static void verifyValidAssignment(final int numStandbyReplicas, final Harness harness) {
        final Set<TaskId> statefulTasks = harness.statefulTaskEndOffsetSums.keySet();
        final Set<TaskId> statelessTasks = harness.statelessTasks;
        final Map<ProcessId, ClientState> assignedStates = harness.clientStates;
        final StringBuilder failureContext = harness.history;

        assertValidAssignment(numStandbyReplicas, statefulTasks, statelessTasks, assignedStates, failureContext);
    }
Flip the cluster states from "assigned" to "subscribed" so they can be used for another round of assignments.
streams/src/test/java/org/apache/kafka/streams/processor/internals/assignment/TaskAssignorConvergenceTest.java