private static Config config(List<SystemStream> inputs, Map<String, String> extraConfigs) {
    Map<String, String> configMap = new HashMap<>();
    configMap.put(JobConfig.JOB_CONTAINER_COUNT, "2");
    configMap.put(TaskConfig.INPUT_STREAMS,
        inputs.stream().map(TestJobModelCalculator::taskInputString).collect(Collectors.joining(",")));
    configMap.putAll(extraConfigs);
    return new MapConfig(configMap);
  }
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