private static TaskModel taskModel(int id, int partitionForSystemStream0, int partitionForSystemStream1) {
    return new TaskModel(taskName(id),
        ImmutableSet.of(new SystemStreamPartition(SYSTEM_STREAM0, new Partition(partitionForSystemStream0)),
            new SystemStreamPartition(SYSTEM_STREAM1, new Partition(partitionForSystemStream1))), new Partition(id));
  }
Unfortunately, we still need powermock for testing the regex topic flow, since that flow checks for a specific
rewriter class, and setting up the support for that specific class is too cumbersome.
Many of the tests do not need powermock.
samza-core/src/test/java/org/apache/samza/coordinator/TestJobModelCalculator.java