@Override
  public Map<String, SystemStreamMetadata> getSystemStreamMetadata(Set<String> streamNames) {
    Map<String, SystemStreamMetadata> metadata = new HashMap<String, SystemStreamMetadata>();

    for (String streamName : streamNames) {
      metadata.put(streamName, new SystemStreamMetadata(streamName, systemStreamPartitionMetadata));
    }

    return metadata;
  }
A SystemAdmin that returns a constant set of partitions for all streams.
samza-test/src/main/java/org/apache/samza/system/mock/MockSystemAdmin.java