StreamApplication getBroadcastOnlyStreamApplication(Serde serde) {
    return appDesc -> {
      MessageStream<KV<String, Object>> input = appDesc.getInputStream(input1Descriptor);
      input.broadcast(serde, "b1");
    };
  }
Unit test base class to set up commonly used test application and configuration.
samza-core/src/test/java/org/apache/samza/execution/ExecutionPlannerTestBase.java